Yandere Meruko-chan wa Senpai ga Osuki

Synopsis

I like you senpai ♡ I don't need anything else... Meru used to think love was a trifling matter, but then she met a petite "senpai" with a strong sense of justice and fell in love. She's very affectionate for senpai, but her love may be going a little bit overboard. (Source: Ichijinsha, translated)