Easily Forgiven: Shiki seems quite easy to forgive Neku for nearly killing her on Day 2. Granted, he was being an idiot, getting himself in a bad sitaution as well but even so.
This happens again on Day 4, after Rhyme's death when Neku basically lashes out on the idea of friendship and Shiki calls him out on this, saying he was no different from the Reapers. She later admits that it was kinda harsh.
Justified as their situation required cooperation and left no room for bad blood between Partners. Surviving the week took priority on personal feelings.
Emo Teen: Lampshaded in Another Day. "Must... fight... emo urges..."
Even the Guys Want Him: Ignoring the Ho Yay vibes he gets from Joshua for a moment, there's one point in Week 2 where Minamimoto starts following him and Joshua around, and Joshua wonders aloud whether it's because he's taken a fancy to Neku.
Also, the various male clerks met throughout the game start getting a little friendly to Neku after their FSG meter rises.
Freudian Excuse: In Another Day, it's suggested that his issues stem from waiting to meet a friend, only to find that his friend had died in a car accident. This may or may not apply in the main game, since after Rhyme gets erased, he thinks it is vaguely familiar, but is unable to remember the exact incident.
Improbable Weapon User: Pins! Most Players are limited to a couple, but Neku can use all of them, including Pins that burn, throw things around, cut, shoot mind bullets, and conjure cans of soda that, uh, heal you. And that's just the starter set.
Ineffectual Loner: Enforced example. If Neku doesn't team up with a partner and learn to cooperate with them, he'll get erased.
I will Find You: Finding Shiki, becomes Neku's entire motivation for winning the game AND putting up with Joshua during the second week.
Jerk Ass -> Jerk with a Heart of Gold: Starts out as incredibly cold toward other people and only concerned with himself, but grows into a more caring individual, albeit one with limited patience for Joshua and Beat.
Psychic Powers: He uses a varied collection of pins to combat the Noise.
Real Men Wear Pink: The Lace Bonnet is a lolita headdress, and the Dragon Lady is a Qipao. They both give bonuses to Neku only. That has some interesting implications, considering character-specific bonuses are normally from items the characters themselves like.
Green-Eyed Monster: She was jealous of her friend Eri, but gets over her issues after hearing Eri talk about her in Day 6.
Heroes Want Redheads: Shiki meant that much to Neku by the end of week one, that she was made his second entry-fee. Subverted twice over: she's not really a redhead, and Kitaniji made her the entry fee because he couldn't revive her. However, since Neku is a redhead...
Hey You -> First Name Basis: Neku often calls her "you" or refers to her as "Stalker", but refers to her by her first name after they win against Higashizawa, much to her pleasure.
A mysterious boy who showed up in the UG unexpectedly. Despite his air of arrogance and secrecy, his knowledge of the UG becomes helpful to Neku... when he feels like giving it. Has a long history with Hanekoma.
Cutscene Power to the Max: His "Jesus Beam", when it's first introduced, kills a Taboo Rhino almost instantly. While it is quite powerful and borders on Game Breaker, it would normally take at least a full combo to do so (and, the opponent being a Taboo noise, Joshua would need the light puck).
Magikarp Power: When you first get him, he's... not quite as good as Shiki was. He doesn't deal damage until he completes a combo chain and his sidestep isn't anywhere near as useful as Shiki's block. When you get the camera upgrade for his phone, he's a bit better, as he gains the ability to stun enemies, but he's still not very powerful. Then, when he starts levitating, he easily becomes the best partner in the game.
Willfully Weak: Averted and justified via Secret Reports. Since he's from a different plane, it causes him to look much younger, lose several of his abilities, and lowers his power output. However, this lets him look like he's a participant in the game, so the Reapers completely ignore him while he makes his own plots.
A hot-blooded young skater who'll go out of his way to protect his friends, no matter the cost to him. While Neku likes to keep his thoughts to himself, Beat will always say what's on his mind.
All There in the Manual: The manual outright says Neku will eventually partner up with him no matter what. In fact, the order Neku partners up with his three allies are in order: Shiki, then Joshua, then Beat.
Determinator: On the 7th day of his week, he starts to fade out due to Not having erased any Players or scored any other points as a Reaper. His reaction? He just "pulls himself together" and keeps on fighting.
Difficult, But Awesome: You'll either hate or love his Fusion Star mechanic. If the cards are properly placed, you can potentially get enough stars for a Level 2 special move in a single combo, but it's often hard to find the cards you need, and you lose all of them if you take too long.
Fragile Speedster: He certainly knows how to skateboard, but doesn't do it in a way that could be called "safe." He's also incredibly fast on his board while he's a Reaper, but doesn't have a lot of defense.
Glass Cannon: Same as the above; great at damage-dealing, not-so-great at damage-taking.
Heroic Self-Deprecation: He doesn't hold a very high opinion of himself at all. This is after seeing how his actions ended up hurting his sister the most, which was something he never wanted.
Hot Blooded: Although Beat claims that before he came to the UG, he was rather laid back and would only take things at his own pace.
Nice Hat: A black hat with a large skull design. It matches Rhyme's hat nicely.
Off Model: A very minor example. He is shown wearing a silver band on his right ring finger on the game's cover art, but it is absent from his sprites and the rest of the game's promotional art. In-game, the times he's shown wearing it can be counted on one hand.
Taking the Bullet: Tragically tried doing this to save Rhyme from getting hit by a car, but managed to get them both killed instead. A more successful version of this happens later on when he saves Neku from an unexpected attack during the final moments of the game.
Sacrificial Lamb: She gets erased in the first week by falling into a not-so-obvious trap set by Kariya and Uzuki.
Satellite Character: An odd justified version of this for Beat. Her fee for entering the UG was unspecified (and according to the Secret Reports, gone forever, because she didn't make it to the end of the week), Beat's fee was her memories of him.
Big Bad: Uzuki in Another Day. She was being used by Higashizawa the whole time, though.
Brilliant, but Lazy: Kariya has refused several promotions because he prefers working on the field. Beat is rightfully afraid of fighting him.
Cool Shades: Kariya wears a cool-looking pair of orange-tinted shades.
Can't Catch Up: After Uzuki's defeat, she reveals that the reason she's so desperate to go up on the ranks is because she feels guilty for Kariya refusing his own promotion just so he could keep hanging out with her. In her own words:
Uzuki:I don't wanna be your freakin' ball and chain!!!
Graceful Loser: More in regards to Kariya, but Uzuki will follow if she must. When Neku and Beat defeated them, they were willing to hand over what the Players wanted, before it turned out to be fake, which not even the Harriers knew.
Karma Houdinis / Easily Forgiven: Neku, and Beat, of all people (in fact, especially Beat, who insisted they be spared), were pretty quick to forget that these were the guys who erased Rhyme in the first place. Though they were Affably EvilGraceful Losers shortly before and willing to hand over the Rhyme pin.
Ungrateful Bitch: Uzuki complains if Neku saves her from Taboo noise, while Kariya is relatively appreciative.
Unholy Matrimony: They don't get married, but one of the later conversations reveals that the reason Kariya doesn't advance through the ranks isn't just laziness, it's also so he can be with Uzuki. Her reaction hints this isn't unwelcome.
Although she still strives to advance herself so that then Kariya could advance with her, and she wouldn't feel like she's dragging him down.
Acting as a proxy Game Master for Kitaniji on the first week (Shiki's chapter). He chooses to hide himself from the players until the 7th day and attempts to pound them to pieces with his immense strength.
Big Bad: The REAL Big Bad of Another Day, having used Uzuki and the Black Skullers to "purify" Tin Pin.
The Game Master on the second week (Joshua's chapter). Minamimoto is a considered a "loose cannon" by the other Officers because he prefers to work by his own rules, rather than those of the game. He's called that for good reason, too: He's crazy and wants to replace Joshua as the Composer. He's also quite fond of math.
Badass Bookworm: The dude trash talks people with math and kicks everyone's asses for the fun of it.
Catch Phrase: "SOHCAHTOA" (this is actually a pun on the Japanese phrase "Sō ka?", meaning "I see", "Is that so?", et cetera), "So zetta slow!" ("zetta" is the prefix for 10^21, or sextillion) "CRUNCH! I'll add it to the heap"... he's got a lot of these.
The Conductor and direct superior of the Reapers. Because the Composer has long been absent, he has asserted control over the Game, and makes sure that everyone, Player and Reaper alike, play by the book. However, it hasn't stopped him from imposing his own "penalties" on Neku for violating the game's rules.
Anti-Villain: Type III. His entire scheme was conceived as an alternative to having Joshua erase Shibuya.
Well-Intentioned Extremist: He was actually playing his own game with Joshua, the Composer, to determine the fate of Shibuya. And if Joshua wins, Shibuya is destroyed. And guess what? Neku was playing on Joshua's side. Oops!
The "Cute Reaper" exclusively in TWEWY: Solo Mix. Does nothing but hang around in the Scramble Crossing, and lets the player buy certain items for real-world money.
Broken Pedestal: Neku initially sees him as a good source of advice, and is amazed to learn that he's CAT, but his faith in him is shaken as he believes that he is the Composer. It ultimately turns out that while he has had a hand in the backstory behind the game, his actions were ultimately for the goal of preventing Shibuya from being erased.
A pair with uncertain circumstances surrounding their death. Both are genuinely nice people, who tell Neku not to give up hope after what happens to him during the second week. Hinted to be a couple but never explicitly mentioned what their relationship is.
Dark Horse Victory: While Neku considers his semifinal Tin Pin Slammer match against Shooter the lynchpin of whether or not the Players are erased that day, Sota ends up winning in the finals. With help.
Eri is Shiki's best friend. Shiki uses a picture of Eri and herself as the wallpaper for her cellphone. Turns out that Shiki is actually the black-haired girl in the picture and that Eri is the one who normally looks like Shiki looks right now. Eri is described as charismatic and popular and she thinks of Shiki as a great friend and seamstress with a keen eye for details.
Glowing Eyes of Doom: See above. He also gets them in Week 3, Day 7 if you enter his shop, under the effects of the Red Skull Pin, though he manages to snap out of it.
Hypocrite: He hates the Shadow Ramen store for deviating from traditional ramen recipes, only to realise that he's been doing the exact same thing himself.
Retired Badass: In "Another Day", he turns out to be the elusive Dr. Pin Sr.
Makoto "Mick" Miki
Originally a timid and unsuccessful businessman, he quits his job for Gatito (or, at least, a subsidiary of them) and opens up the Shadow Ramen store in the second week to rival the Ramen Don shop. He is also responsible for helping spread around the Red Skull pins, their purpose becoming much clearer by the end of the game.
Leader of the band Def Märch, which also includes fellow Reapers B.J. and Tenho.
Anti-Villain: Type IV. 777 is pretty nice overall and seems more worried with his band and bandmates than actually being a Reaper. The only time he fights you, he's even honourable enough to give you a key after Neku spares him. His subsequent erasure by Konishi is used as a big Kick the Dog moment.
Everything Is an Instrument: Tenho steals the band's microphone, which, in turn, is swapped by Minamimoto for his megaphone. The band ends up attempting to incorporate the megaphone into their act.
A pair of schoolgirls who are good friends. Lately, their friendship has been put under some strain when Ai suspects Mina is trying to steal her crush, Makoto, away from her, although it all gets cleared up with Neku and Shiki's help.
Clingy Jealous Girl: Ai, to an extent. However, it turns out she does appreciate her friendship with Mina deeply.
Friendship Moment: Mina buys some tickets to a Tin Pin Slammer event to give to Ai so she can go out with Makoto. Unfortunately, Ai misunderstands her intentions at first, but apologizes as soon as she finds out.
Green-Eyed Monster: Ai gets suspicious of Mina the minute she sees her talking to Makoto alone.
Another Day Tutorial Guy/ The Wizard of Slam/Shinji Hashimoto
A Reaper-looking person in Another Day who teaches Neku about Tin Pin. He's one of the Black Skullers and fights Joshua as the first opponent. He's ultimately revealed to be Shinji Hashimoto himself and is the True Final Boss of the Tin Pin sidequest if you beat Shooter.
Big Good: Of Tin Pin in the Another Day universe and possibly the main universe.
The Chessmaster: He helped set up the events of Another Day so the Omega Slammer would be completed.