Kimi wo Utsushite Hanasanai

https://www.cmoa.jp/title/305690/
Rio is a completely average high school second-year, while her best friend Katsuki is pretty enough to turn everyone's heads. Sometimes Rio feels like she's just there to make Katsuki's beauty stand out better... or even worse, that she's invisible to the whole world. Discouraged as she is, Rio was holding onto a faint hope of love with Haruta, the only person at school who ever seems to notice her. When she realizes one day that he has a crush on Katsuki rather than her, she's so upset that she flees the classroom, wishing she could finally just disappear for real. But, while she's nursing her hurt feelings, someone comes and finds her; it's none other than "the reaper," aka Echizenya, the gloomy guy who's always hiding away in the corner creeping out their classmates. Enjoy this adorable will-they-won't-they romance between the "plain best friend" and the secret hottie undercover as the class weirdo!