Tenran no Memento

Our main character is a lethargic and cool high school student named Akashi Chika. Chika spends his boring day-to-day life peacefully, however he has this dream that he often see in his sleep. It's a dream about a girl, a very neat and clean girl wearing a kimono. Without even knowing her name, Chika can't help but to feel a nostalgic feeling towards her. While he's living his daily life with this matters still in his mind, a somewhat grotesque being, completely out of this world appears!! This incident fundamentally overturns Chika's ordinary days, and he starts to recall his past memories which have been sealed.