Follow TV Tropes


Light Novel / Only Sense Online

Go To
"Only one"

Only Sense Online, also known as OSO, is an ambitious Virtual Reality MMORPG that offers players a high level of customization via its "Sense" system. Each player gets to choose from a vast list of talents known as Senses and they are encouraged to create their own Sense build for an "only one play style".

During the official launch of Only Sense Online, Shun, an Ordinary High-School Student, is compelled by his best friend Takumi and younger sister Miu, both hardcore gamers and beta testers of OSO, to join them in the game. Hilarity Ensues, when the game system mistakes his sex and generates a female avatar for him, which he further complicates by accidentally giving himself a feminine-sounding handle "Yun". As a complete novice player, Yun picks up a set of unpopular Senses which his much more experienced companions label as trash. Undeterred by their harsh words, Yun decides to keep his Senses and experiment with them, embarking him on a journey where he would explore the richly-designed game world, meet new friends, face challenges and actually thrives in-game… all alongside with him constantly trying (and failing) to convince other players that he is not a girl!


Only Sense Online is an ongoing Light Novel series written by Aloha Zachou, and is published by Fujimi Shobo. Its Slice of Life approach to the VRMMORPG concept makes it Lighter and Softer compared to other works of its genre, such as .hack//SIGN and Sword Art Online, although it is still exciting in its own right. Only Sense Online has a manga adaptation, which is also published by Fujimi Shobo.

This series provides examples of:

  • Acquired Poison Immunity: Some players deliberately take Bad Statuses to level their Resistance Senses. In "Forest Camping Game" event, a lot of players ends up accidentally level up poison resistance due to them not having the skills to identify and prepare poisoned food and resorting to eating everything they can find. It's traumatized quite a number of players.
  • Affectionate Nickname: After the "Forest Camping Game" event in volume 2, Yun acquires the nickname "Young Beasts' Nanny", or simply "Nanny", thanks to his conspicuous efforts to save and take care of the young beast NPCs during that event. Needless to say, he dislikes that nickname intensely.
  • Advertisement:
  • All There in the Manual: Subverted, as the game is poorly documented by the developers, with most guides and resources coming from wikis and forum guides assembled by beta players and built upon once the game goes into official release. Most players treat those guides as a de facto manual, including the infamous tiering of the Senses. But then played straight for anyone with the Linguistics Sense, as the in-game library is full of thorough documentation of the game's workings and numerous crafting recipes that most players like Yun had worked out on their own. All of which was missed for months because it was gated behind a trash Sense.
  • Amazon Brigade: Myu's usual in-game party is composed of six (including her) Gamer Chicks of similar ages. All of its members have different specializations, which complement each other very well, and their excellent teamwork makes them a fearsome force in-game.
  • Artificial Intelligence: One of the selling points of OSO-the-game is its highly advanced artificial intelligence, to the point that Yun sometimes muses whether the NPCs he is interacting with are in fact controlled by actual humans.
  • Attractive Bent-Gender: Thanks to the automatic body correction applied to him after the system misidentified him as female, Yun appears in-game as a long-haired beauty. He is quite annoyed by other male players hitting on him in-game.
  • Beach Episode: There is a side-story of Yun, Toutobi, Magi, Lucato and Myu at a beach in OSO.
  • Bigger on the Inside: All guild halls featured in OSO (【Crafting Guild】 and 【Eight Million Gods】) so far are noted to be bigger on the inside. However, most in-game buildings avert this trope, which let Taku and Yun discover a secret quest in the library when they realized it was too big on the outside, with another set of windows beyond the "back corner" Yun had settled in to read.
  • Bottomless Quiver: Averted. One of the reasons why the bow is disdained in OSO is because arrows are one-use consumables and acquiring them from shops is very inefficient.
  • Breakable Weapons: Equipment in OSO have durable ratings, which if sufficiently damaged can break. Luckily, it is usually possible to repair broken equipment at a cost.
  • Brother–Sister Incest: One nearly happens by accident in the beginning of Volume 4: after Yun and Myu got hit by Charmed status effect while testing out potions, Myu suddenly pushes Yun down and seems like she's going to have her way with her brother until Magi walks into them.
  • Calling Your Attacks: All characters in this series have the habit of calling out whatever skills they are preparing to use, presumably because the skills are all voice-activated.
  • Cassandra Truth: Despite his constant vehement protests otherwise, nobody besides his real life acquaintances actually believes that Yun is not a girl.
  • City with No Name: Several in fact. The towns are simply called "the first/second town."
  • Collector of the Strange: Yun builds up a collection of Cursed Objects after the Summer Camping Event.
  • Colossus Climb: The Grand Rock found in the highlands can be climbed.
  • Complacent Gaming Syndrome: In-Universe, this created the harsh tiering of Senses that left many considered "trash." The majority of players treated OSO as any other MMO, devoting themselves to the combat grind while ignoring numerous (poorly-documented) subsystems that didn't have an immediate benefit. Even crafters mostly settled for making equipment and letting NPC vendors handle consumables. Then the GMs shook things up with a number of formal and informal events designed to force the player base out of its complacency - letting NPC vendors sell out, instituting a hunger/satiety system that suddenly made the "useless" Cooking Sense essential, the Forest Camping Game which demanded low-tier Senses to prosper, and so on. Yun, being one of a few players to heavily invest in those skills from the start, has a massive advantage over the others.
  • Cool, but Inefficient: The most favorable opinion most people have for archery: sure, it looks neat, but it has serious problems, from poor range and accuracy to arrows being consumable items. It turns out that archery, like other combat Senses, works best when paired with Senses that make up for its limitations, but nobody in the closed beta had figured out what the best support Senses were. Meanwhile, consumables are essential for everyone and so the cost of arrows turns inconsequential next to, say, the MP potions mages eventually need to keep going. After the first book Yun's arrow worries disappear since it's just one (very small) part of prepping for combat. Running out of ammo is an everpresent issue, however, especially in long battles, which is why Yun eventually picks up kitchen knives as secondary weapons.
  • Crippling Overspecialization: Most OSO players have combat-oriented Sense builds, which are generally sensible in a game where combat is an important aspect. However, this becomes a problem during the "Forest Camping Game" event when survivalist-based Senses become equally important and suddenly players are caught in a situation where Everything Is Trying to Kill Younote  and they have no adequate countermeasures besides combat skills, which Myu's party learnt the hard way.
  • Cross Player: invoked Although this option is not available by default in OSO, Yun becomes one thanks to a system misidentification by the game. His real life acquaintances treat this as a case of Good Bad Bugs, much to his chagrin.
  • Cuteness Proximity: All of the young beasts that appear during the "Forest Camping Game" event invoke this to whoever who gets close to them.
  • Design-It-Yourself Equipment: Experienced crafters in OSO are able to customize the equipment they make, including naming them whatever they want.
  • Developer's Foresight: As the game goes on, it becomes increasingly clear that there are no truly trash Senses, with content, useful abilities, and helpful shortcuts hidden behind everything. It's mind-boggling how much the developers made that probably nobody has seen yet because it's gated behind something "useless."
  • Digital Avatar: All players of OSO control one within the game's Cyberspace.
  • Draw Aggro: There are some Sense skills that do this.
  • Driven by Envy: Played for Laughs during the PvP Tournament organized by the 【Crafting Guild】 in volume 5, when a group of participants with unlucky love lives form an ad hoc alliance and gang up on participants who they deem lead wholesome lives in and outside the gamenote , in the style of the FFF.
  • Dude Looks Like a Lady: Yun's real life self looks feminine enough that he had been able to crossdress once in the past without a hitch. This is probably the reason why the game system mistook his sex in the first place. This applies even better for Lyly since Lyly is male in-game and can still crossdress without problem.
  • Elemental Crafting: Present though downplayed. For example, most people who use metal gear use iron or steel, though there are the more powerful Fine Iron and Mithril. Most better materials are Random Drops from powerful enemies and bosses until people can acquire high-level mining skills. Yun discovers that Alchemy can bypass the boss drops by combining a lot of a low quality material into a little of something better (and is strongly implied to be the reason Myu was able to get her fancy armor far earlier than expected).
  • Encounter Repellant: The Insect Repelling Incense does this for insect type mobs.
  • An Entrepreneur Is You: OSO has a well-developed Player-Generated Economy, which gives players the choice to focus almost exclusively on running a business in-game.
  • Fairy Companion: Various people gain these in Volume 6 during the quest to save the Fairy Queen.
  • Feathered Fiend: The Cockatrice in the Highlands area.
  • Fictional Video Game: The titular Only Sense Online.
  • Field Power Effect: Known as terrain effects in OSO. Areas such as the forest and plains don't have them. Wetlands have something like 【SPEED Decrease】. Dungeons have traps and caves have darkness. The Horia Cave gives the 【Confusion】 bad status.
  • First Town: The starting town in OSO is literally named as such.
  • Fountain of Youth: Yun accidentally created some "Age-Faking Medicine" in volume 6 after his fairy companion pranked a potion he was brewing, which inevitably exploded and drenched him in the process. His avatar transformed into a little girl and he became stuck in that form for an extended period of time before its effect expired naturally.
  • Gamer Chick: Virtually all female characters in this series are one, considering they are all dedicated players of OSO.
  • Healing Potion: The standard healing method in the game when one doesn't have recovery magic. There are different levels for them and they decrease in effectiveness depending on how much SP a player has in stock. There are also potions that heal that are not affected by the SP amount: Blue Potions and Yellow Potions.
    • One of the first things Yun crafted in OSO, one of them is the Blue Potion. He turns out to be so good at crafting them that he is known as the "Mysterious Blue Potion Vendor" for a period of time due to having them distributed earlier than anticipated in the game and it is not publicly known who was the one making them.
  • Hero of Another Story: Yun's sisters and his best friend are all veteran players of OSO and their exploits in-game are all interesting stories in their own right, although they will never be shown directly in this series.
    • Myu eventually received a spin-off story that shows her perspective of how she formed her party.
  • Heroes Prefer Swords: Swords are very popular weapons in OSO, and are the weapons of choice for quite a few major characters, such as Myu and Taku, and it is implied that both of them are trying to invoke this trope by using swords. Even Sei uses a spell to give her a sword she can wield with her Staff Sense.
  • Hoist by His Own Petard: The MPKer who tried to kill Yun and Myu's party in volume 1 by luring a horde of monsters against them ended up being overran by that very horde after Yun cast a speed debuff against him to slow him down.
  • A Homeowner Is You: It is possible for players to build their own house in OSO by purchasing land in-game and spending huge amounts of in-game currency to build on it.
  • Hot Springs Episode: Double Subverted in volume 8, when Yun accompanied the 【Eight Million Gods】 in their guild expedition to the Volcanic Area and encountered a hot spring. Initially, Yun refused to join with the female members of the expedition into the hot spring out of ethical concerns, and readers are only given Yun's imaginations of what could have transpired in his absence. However, later in the volume, Yun decided to take a quick dip into the spring when he thought he was alone but was then spotted by Mikadzuchi and Sei, who promptly joined him, much to his shock.
  • Hub City: The aforementioned First Town serves as this for most OSO players, as it is also the location where most crafters set up their shops in.
  • Impossible Item Drop: During the "Forest Camping Game" event, Yun defeats a Western Bluefin Tuna monster, which drops... a set of western cooking tools.
  • An Interior Designer Is You: All players who own shops or houses in OSO can customize them according to their own desires.
  • Item Crafting: OSO has a very elaborate item crafting system, which necessitates the existence of players with crafting-oriented Sense builds. Fortunately to save one's sanity, for most consumables you only have to craft them directly once, then can spend Mana to mass-produce (slightly lower-quality) copies in a short time. There'd be no keeping up with the demand for potions otherwise.
  • Job System: The Sense system in OSO combines aspects of this with a Point Build System, wherein the number of Senses a player can use at any point of time is capped at 10, however as they increase their mastery of their Senses, they can acquire new Senses which they can then freely swap with their existing Senses.
  • Lethal Lava Land: The Volcanic Area introduced in volume 8 is one, being filled with lethal steam vents, boiling oil pools and other dangerous hazards.
  • Lighter and Softer: Compared to the likes of Sword Art Online or .hack or any series that has the games becoming reality for the characters, this series is very lighthearted and just follows the normal everyday gaming life of a guy.
  • Living Shadow: The Darkman boss in the Fourth Volume.
  • Magikarp Power: All of the skills Yun picks turns out to be quite useful; they just need a lot of time and effort to level up, which he does. For example, Yun's Hawk Eyes Sense is widely derided in OSO because its immediate effects - extended vision and night vision - are easily substituted with other more useful Sensesnote . However, Yun quickly discovers, with some insight from Taku, that Hawk Eyes is in fact a targeting Sense, and allows its user to cast spells as far as the range of the extended vision it provides. After it reaches level 50, it can be upgraded into Sky Eyes, which enhances its effects even more and also provides new effects, including the ability to perceive enemy attacks in Bullet Time.
  • Mana Potion: There are potions that restore MP.
  • Marilyn Maneuver: In volume 5, when Yun was forced to help the 【Crafting Guild】 to host the PvP Tournament while cosplaying as a nun, an ill-timed draft generated by the opening ceremony's special effects lifted his skirt up, much to his absolute embarrassment.
  • Marshmallow Hell: Magi deals it to Yun and Lyly on two separate occasions, although it was an accident for the latter.
  • Medieval European Fantasy: The world of OSO is described to be a variant of this.
  • Money Sink: The game is full of them, ranging from the constant need for equipment repairs, rental costs for shops and homes, membership fees for various services such as libraries, and hefty expenses for founding and running a player guild. Yun is incredibly susceptible to these, as he's constantly blowing piles of cash on land, shop improvements, armor repairs, and new tools. Or paying people after accidentally breaking their stuff.
  • Monster Town: The dungeon in the Volcanic Area turned out to be a full-fledged town populated by demonfolk, aptly named the Demonfolk Resort.
  • Mundane Utility: As he becomes more used to the game, Yun finds out that he can make use of OSO's Virtual Reality and practice his real life baking skills without spending actual money on baking ingredients. Some other players also use the game for simulation of real-life activities when time constraints makes them unable to do it in real life, such as mountain climbing or fishing.
  • Nonstandard Skill Learning:
    • Normally one learns a new Skill or Art when certain Senses reach a certain level but there are others that have some hidden requirements.
    • Shock Impact is learned when one hits an enemy with high defense 100 times using arts.
    • Fifth Breaker is learned when one uses Delta Slash 100 times.
    • Ingredient Knowledge is learned when 【Cooking】 is level 10 or higher and when one subjugates 100 enemies with Cooking-type equipment.
  • Optional Stealth: There are Senses and skills that give players stealth and materials to add it to equipment.
  • Player Archetypes: Many of the characters of the series can be a combination of archetypes but leaning more to one side than another.
  • Player-Generated Economy: Although it is possible to acquire basic equipment and consumables from NPC-run shops in OSO, the best equipment and consumables are all made by the players themselves, which drives the creation of a vibrant player-based economy.
  • Player Headquarters: All player-owned houses in OSO can take up this role, especially after they are fully decorated.
  • Player Killing: Some players take part in this. It is a bit different than Player Versus Player. The PK'er takes half the money of the player they killed and the PK'er is subjected to a penalty of losing levels if they are killed afterwards.
  • Player Versus Environment: Most of the combat in OSO.
  • Player Versus Player: Players can partake in PvP. They send invites to players they wish to fight and set rules on how the winner is decided.
  • Point Build System: Sense points (SP), are what players use. Players start with 10 SP to choose their initial 10 Senses. For every 10th levels a Sense reaches, a player gains 1 SP. Players can spend SP to acquire new Senses or grow Senses to higher versions. Stockpiling certain amounts of SP unlocks new Senses to spend SP on.
  • Pose of Supplication: Sei once fell down to her knees in dismay upon learning about how Yun scored yet another Rare Random Drop in OSO.
  • Potion-Brewing Mechanic: Thanks to OSO's elaborate Item Crafting system, potion-making is a very intricate process, and it is actually possible to greatly enhance the efficacy of a potion by performing a whole series of intermediate steps, such as drying the potion ingredients before mixing them. Yun accidentally becomes the game's first dedicated potion brewer due to the mechanic being dismissed as not worth the time by other players.
  • Pre-existing Encounters: How mobs are in OSO.
  • Priceless Paperweight: In volume 8, Yun used a lithographic stone that was inscribed with rare and valuable potion recipes as a lid to secure a barrel of pickled vegetables he made after he deciphered those recipes. The stone ended up printing the inscriptions onto the pickles themselves!
  • Puppeteer Parasite: The Thorn Token monsters do this to others to use their bodies in the sixth volume.
  • Rocket Jump: Yun devised a variant of this during the raid boss encounter of the "Forest Camping Game" event when he propelled himself further into the air by activating a hand-crafted magic gem enchanted with an explosion spell.
  • Running Gag:
    • Yun retorting to other OSO players (and failing to convince) that he is not a girl.
    • Letia and her constant demand for food.
  • Scrappy Weapon: invoked The bow is widely derided in OSO because of its horrible cost-to-performance ratio. It requires a constant supply of arrows, which are one-use consumables, and its accuracy is terrible compared to other weapons because it requires a high dexterity stat to be effective, which most players do not usually obtain due to their heavily combat-oriented Sense builds raising their attack stat instead.
  • Ship Tease: The author enjoys placing Taku and Yun in compromising positions, and the latter's vehement denials of any special relationship between the both of them only entrenched the impressions of onlookers that "she" is acting like a Tsundere. There are also quite a few between Yun and Magi.
  • Shout-Out: There are a few.
    • Volume 1
      • In chapter 3, after selling stuff he crafted to Magi, Yun splurged so much of his money that you would think he is in a MasterCard ad.
      I've had enough money. I've still had some left over after buying a portable furnace. ——800G
      I've had enough money. Again I've still had left over after buying a higher level polishing kit. ——1500G
      I've had enough money. Once again I've still had left over after buying a higher level Synthesis kit. ——1500G
      I've had enough money. So I bought ten sets of Iron Arrows. ——300G
      The result, what remained was——630G
      What I obtained with it is priceless. No wait!! I splurged too much. I'm broke again. It means I need to craft again.
      • When Myu's party addressed the MPKer that was trying to kill them in volume 1 as "Train Man", Yun wondered whether he had anything to do with a certain unique romance novel.
  • Silver Has Mystic Powers: Like in many games, silver weapons are effective against undead.
  • Single-Use Shield: Yun has an item called the "Substitute Gem's Ring'', which allows him to completely negate a couple of attacks, regardless of their power, at the cost of one gem.
  • Slice of Life: This series is a slice of Yun's everyday life in and out of OSO.
  • Spin-Off: Only Sense Online the Silver Muse follows the adventures of Myu.
  • Status Effects: There are eight standard status effects in OSO and a few other kinds as well.
    • The eight standard status effects:
      • Bodily Statuses: 【Poison】, 【Paralysis】, 【Sleep】 and 【Stun】. The DEF stat helps determine the resistance.
      • Spiritual Statuses: 【Curse】, 【Charm】, 【Confusion】 and 【Anger】. The MIND stat helps determine the resistance.
    • Other statuses: 【Drunkeness】
  • Talking Is a Free Action: Characters will periodically have some rather lengthy chats on strategy in the middle of fights, to the point that it can strain disbelief for anyone familiar with MMOs or the pace of action RPGs in general.
  • Too Awesome to Use: The fairy-possessed ring, a reward from a limited quest featured in volume 6, grants its bearer three wishes from the fairy possessing the ring before disintegrating. Yun, overwhelmed by all the potential wishes, was hesitant to use it at allnote .
  • Turtle Island: The Grand Rock is a tortoise mountain found in the highlands. It has mining points and cockatrice living on it's shell.
  • 20 Minutes into the Future: Besides the existence of a mature Virtual Reality technology which enabled the creation of OSO, there are no other notable differences between Only Sense Online's world and the actual world.
  • Underwater Ruins: Yun explores a cluster of such ruins during the "Forest Camping Game" event in OSO, which turns out to provide important details on how to complete the event.
  • Unknown Item Identification: Most item drops and collectibles in OSO have to be appraised by players with the appropriate Senses before their full effects, or even identities, are uncovered.
  • Unwanted False Faith: Played for Laughs in volume 8, when Myu's party prayed to Yun before playing the Demonfolk Resort's lottery, since they believe him to have been blessed by the Random Number God. Amusingly, it did raised their luck coincidentally(?) and other players end up trying to worship Yun as well before playing the lottery!
  • Womb Level: The Grand Rock has a dungeon inside it.
  • World of Technicolor Hair: Many OSO players opt to give their player avatars fantastic hair colors, such as Myu's white hair, and Sei's light blue hair. It makes Yun and Lucato stand out more for having realistic black hair.
  • Year Inside, Hour Outside: The "Forest Camping Game" event takes place in a special OSO server in which the flow of time has been stretched by about 80 times. This enables the event to last for a week while only taking up 2 hours of real time.
  • You Called Me "X"; It Must Be Serious: Mikadzuchi, the guild master of 【Eight Million Gods】, always addressed Yun as "Missy"note , which he always tried to retort. However, after Yun saved her from a potentially deadly boss attack in the Demonfolk Resort's arena in volume 8, she actually thanked him by name, much to his surprise.