18+ Otome Historic

Toko is a third year high school student who's been active in the ping pong club. One day, the teacher she likes, Katakura-sensei, quit being the ping pong club advisor and went to head the history club. Going to check out the people who 'stole' her precious teacher, Toko finds herself applying to join the history club! The three other members, Ren, Maria, and Naho, might be suspicious of her intentions, but at least she'll be near Katakura-sensei once again!

(Source: MangaHelpers)