Dusk Maiden of Amnesia

Legend states that the ghost of a student who died at Seikyou Private Academy still haunts the grounds to this day... A truth that first year student Teiichi uncovers when he stumbles into that very ghost, Yuuko! However, with no memories of her previous life, she enlists the help of Teiichi and opens a paranormal investigations club to unravel the school’s ghastly mysteries.

Source: Manga UP! Global