Untrustworthy [Yandere JJK x Kakashi!Reader]

Prologue

Sitting in a restaurant, there is a lovely couple, flirting and laughing as they waited for their food. Unaware of the heartbroken female that sits behind them. (Y/n) caressed the ring on her finger, a promise ring given to her by her boyfriend. Like Yuta, she was promised a lifetime of love and care, until they eventually are old enough to be married. "Why..." She muttered as tears dripped onto the table and soaked the fabric that covers her right eye.

Before the couple could kiss, she made herself known, by tossing the ring in between them. "Huh?" They both muttered as they examined the strange item. But, the male's eyes widen in realization, knowing exactly who that ring belongs to. "(Y/n)... (Y/n)! Wat!" Yuji exclaimed as he reached out to her, her back turned to him.

She didn't wait for him, slamming the restaurant door in his face, stopping him from touching her. When he swung the door open, she was gone. "(Y/N)! (Y/N)!" He yelled for her, frantic to find her and explain the "misunderstanding", but he never got to. Meanwhile, the female he had cheated (Y/n) on, picked up the promise ring and slipped it onto her ring finger.

"Hello? What does my cute little sister need~?" Satoru cooed into the phone, giddy as ever. But, his smile dropped when he heard a muffled sob. "Stay there, I'm on my way" he demanded as he strode out of the room, ditching the meeting he was in. "I'm... Fine? It's fine..." (Y/n) reassured through the phone, only to be started by an arm dragging her into a chest.

"Don't lie to yourself, let it out, your big brother is here" Satoru hushed as he rubbed comforting circles on her back. "...You're not my brother," she said, muffled by his shirt. "Only biologically speaking!" He retorted with a large grin, earning an amused scoff from the female. "Now, enough crying! We're getting ice cream!" He exclaimed as he pushed her onto her feet.

"I don't like sweets, you should know this" she grumbled, her grimace hidden behind her mask. "Fine, only this time, I'll buy you black coffee" he groaned, knowing she'll need it. "Black and bitter like my soul, perfect for this shitty day" she joked as they headed to the coffee shop. "Satoru... Thanks" she mumbled as she looked away from him, earning a genuine smile from him.