Miki-san, Daisuki desu!

Kousaka is a quiet, timid boy who's happy enough to go unnoticed by his classmates. But one moment of kindness and concern by a bright and outgoing gyaru starts to change his life.

Originally published on Twitter and Pixiv as Yarisugichau-kei Imo Danshi ga Anego-kei Gyaru wo Suki ni Natta Hanashi.
Now serialised in Kadokawa's Young Ace Up.