Webcomic / My Brother's Not-So Secret Boyfriend

It ain't easy being the Third Wheel.

My Brother's (Not-So) Secret Boyfriend is a Webtoon webcomic created by metaromantic on 25th June 2022.

Contains the following tropes:

• All Guys Want Bad Boys: It turns out Kaito might have a thing for delinquents as evidenced by his huge crush on Maki, a stereotypical Japanese Delinquent with a Cool Bike, and had dressed him up as a shirtless, bandaged yakuza for a Q&A session. In chapter 51, he was even disappointed when Maki didn't have any piercings or tattoos to go with his dyed pink hair.
• Alliterative Name: Double "K"s for Karin Kobayashi as well as her brother Kaito Kobayashi.
• Delinquent Hair: In Maki's biker gang, he, Michi and Itsuki dyed their hair pink, white and blonde respectively while Daiki styled his as a curly pompadour akin to Mondo.
• Diving Save: When Maki is retrieving Karin's backpack from a tree, the branch underneath him breaks. But just before he hits the ground, Kaito swoops in out of nowhere to save his boyfriend from a possible concussion.
• Double-Meaning Title: The "Not-So" in the webcomic's title can refer to both the fact Kaito and Maki suck at being discreet about their relationship (As Karin can attest to) and that they are not actually dating yet let alone boyfriends.
• Friends with Benefits: What Kaito and Maki's relationship turns out to be currently much to the surprise of Karin and the audience since their behaviour up until the reveal would suggest them as lovey-dovey boyfriends. This is because neither of the two had confessed their feelings for one another despite the obvious mutual attraction and chemistry which means the plot now switches to them taking the next step in their relationship through the help of Karin.
• Halfway Plot Switch: The webcomic starts out with Karin's misadventures being an unwitting Third Wheel to her brother and Maki's incredibly unsubtle Secret Relationship until Maki slips out he isn't actually dating Kaito yet so Karin changes her motives to get them together so they would leave her alone.
• Innocently Insensitive: Daiki has this nasty habit of Open Mouth, Insert Foot due to his upbringing around colorful language without a filter. A particular example would be using gay as a slur in front of a closeted Maki, making him very uncomfortable and have second thoughts about confessing to Kaito. Daiki himself doesn't mean any harm as he's beyond stupid to know any better and proves to be incredibly supportive towards Maki after a few lessons from Karin.
• Japanese Delinquents: Maki is in charge of his older brother's biker gang until he comes back from jail. Besides their easy-going leader, the gang consists of "Angry Mom Friend" Michi, grade-A dumbass, foul-mouthed Daiki, the equally dimwitted, reptile-like Itsuki and intimidating but lover of small, cute things Goto.
• One Head Taller: Same-sex example. Even though Kaito is of average height, Maki is the tallest in their class and thus invokes the trope with his boyfriend.
• One-Note Cook: Kaito can only ever make fried eggs to both Maki's amusement since he didn't expect the hyper-competent class president to be unable to cook anything else and Karin's exasperation who had to deal with this egg nonsense her whole life and had to take over cooking duties because of it.
• Pointless Band-Aid: Maki has one plaster over the bridge of his nose to emphasize his delinquent nature.
• The Reveal: Maki discloses to Karin that he and Kaito are not even officially together yet, bringing light to their relationship as more of Friends with Benefits rather than boyfriends that she (and the audience) presumed, and only started seeing each other just the day before the opening scene where Karin caught them kissing for the second time (and the first without public coercion). As a result, the plot shifts from Karin dealing with Maki and Kaito's not-so-secret relationship as a Third Wheel to making it actually happen so they would leave her alone.
• Romantic Wingman: Karin immediately becomes one to Maki once she finds out that he and Kaito are not officially dating, in spite of their constant make-out sessions and mutual crushes, and advises the former to give flowers for his confession since the latter is the romantic type. However, Karin only does this in hopes of finally being left alone and not the Third Wheel forced upon by her brother.
• Supreme Chef: Karin takes up all the cooking duties in the Kobayashi household out of necessity since her brother cannot cook anything other than fried eggs to save his life. As such, she becomes a whiz in the kitchen despite only being 14 years old with her specialty being baked goods.
  Karin: [Texts over a group chat] Whoever compliments me the best, I'm coming over to your house to bake cookies.
  [Several people typing fanatically at once]
  Commentor 1: KARIN MY LOVE
  Commentor 2: Sweet baby sunshine, Light of my life
  Commentor 3: Have i ever told u your eyes are like rubies (Like the Pokémon game).
  Kyoko: You're the best. Oatmeal raisin plz.
  Commentor 4: Kyoko you HEATHEN
  Kyoko: Add in choco chips and nuts too.
  Commentor 5: Goddess in the kitchen
• Whole Episode Flashback: Chapters 30 to 40 were dedicated to how Maki and Kaito came to their current relationship of boyfriends/Friends with Benefits which just so happens to be the day before the beginning of the webcomic (Karin really cannot catch a break as an unwitting Third Wheel).