Tenran no Memento

Akashi Chika, a lethargic and cool high school student, spends his boring day-to-day life peacefully, with the exception of a certain dream that he often sees. A dream about a girl, a very neat and clean girl wearing a kimono. Without even knowing this girl's name, Chika can't help but feel a very nostalgic feeling towards her.

While he's living his daily life with this matters still in his mind, a grotesque being, completely out of this world appears and fundamentally overturns Chika's ordinary days, as he starts to recall his past memories which have been sealed...

(Source: MU, edited)