After orphan Teru Kurebayashi loses her beloved older brother, she finds solace in the messages she exchanges with DAISY, an enigmatic figure who can only be reached through the cell phone her brother left her. Meanwhile, mysterious Tasuku Kurosaki always seems to be around whenever Teru needs help... Could DAISY be a lot closer than Teru thinks?

Teru decides to move out of Kurosaki's apartment, but she wonders if Kurosaki is actually relieved that she's leaving. As she settles in at her new place, trouble comes knocking when an old business acquaintance of her brother's appears...