Djekna Hasn't Died Yet, and We Don't Know When Will She

I have not seen a bigger fool than you, who works more against himself, until you

A high school student whose years of not having a girlfriend is his age, Keiki Kiryuu, suddenly receives a love letter. He is happy he can finally have a girlfriend, but is also surprised because not only is there no sender name but also included is white underwear…??? The cute girls who gather around him are all weird and with reasons!? Who is the Cinderella who sent the underwear?