On a lot of the headcanon books I read, there's usually some yandere headcanons so I though I might as well give them a go but they're not really like full blown "yanderes" if that makes sense. I know it doesn't but I tried my best and I hope you enjoy nonetheless.
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Characters included: Sanemi, Muichiro and Rengoku (if you'd like any other characters let me know or if youd like me to try and expand any more on the characters that are here)
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SANEMI
•Despite him being violent and aggressive towards most, he's a big softie for you and every time he tries to talk to you, he's a stuttering and blushing mess.
•You notice that he always appears at the right time like for example, if you haven't eaten he'll rock up with food, shove it into your hands then stomp away. That's kinda just his way of "keeping you safe."
•You could just be sitting with your friend and all of a sudden, they just run off- that would be due to Sanemi glaring at them. Then he'd just come over and sit beside you like he didn't just scare off your friend.
•Bro literally watches you sleep like you'd just be sound asleep and he rocks up and stares at you and if you wake up, he'll just pat your head until you go back to sleep and grumble away to himself about how stupid this is.
•If you ever go on a mission with a boy, you'll notice that maybe a few days later he just disappears and that's because sanemi "disposed" of him to keep you safe.
MUICHIRO (imagine he's a bit older unless youre around his age idk)
•He's just a little cutie patootie- you're one of the only people's names he remembers so he likes spending time with you.
•He makes you little flower crowns in your favourite colours and puts them on your head and that's his way of showing others that you're "his."
•He's very clingy so he always has to be holding your hand, hugging you, linking your arm with his, ect.
•He's not as violent as Sanemi so if you're with another boy he'll just be all over you or grab your hand or just drag you away altogether.
•He loves to plait your hair and he also enjoys you plaiting his. (Ik that's irreverent but ah well)
RENGOKU
•He's not really a yandere he's just more clingy.
•He loves choosing out outfits for you and doing your hair all fancy and he's surprisingly good at it.
•You don't really get much privacy with him is the only thing because he follows you literally everywhere.
•He always brings up that you two are dating in conversation because he despises when guys hit on you.
•Every time he goes on a mission, he always makes sure to bring you back a gift of some sort.