It's Valentine's Day-and while Domeki is showered with chocolates and cardsfrom girls, Watanuki receives none. To make matters worse, he must also dothe usual chores for Yűko, which includes making chocolate cake for herand Mokona, as well as the treats his boss wants to give away as gifts.But when Watanuki discovers he has a shy and secret admirer who is notquite human, he finds that chocolates can be more than just sweets. Then,after seeing identical twin sisters pass by in the street, Yűko makes acurious remark: that there are chains that only humans can use to bindothers. Watanuki meets the sisters and senses that the relationshipbetween them is not what it seems. . . .