Sasami discovers a DVD containing a project by Kamiomi and the Yagami sisters involving them filming her in secret to record her progress. Putting the somewhat perverted nature of the DVD aside, Sasami can't recall doing any of the actions displayed in the video. As Sasami in the video winds up at a mini live concert, it turns out to be a trap set up by the Tsukuyomi Shrine, in which Sasami's father stabs her third arm and allegedly steals her power of Amaterasu. The video soon reaches its climax involving an all out battle between the shrine, the Yagami sisters and government forces trying to obtain an alien Tama came across. Tsurugi then explains that the DVD was made to explain things to Sasami, who is actually revealed to be the third arm, a sarcoma, who lost her memories and assumed she was Sasami and took her form.
お兄ちゃんの部屋でささみさんが見つけた一枚のDVD。“極秘”と書かれた怪しげなその中身は、社会復帰を果たしたささみさんを応援し、その様子を撮影・記録する『ササミ・ウォッチ・プロジェクト』だった！？邪神三姉妹とお兄ちゃんがこっそり見守る中、与えられた試練（おつかい）をクリアしようとするささみさん。ところが、事態は思わぬ方向へと転がっていき…。
Sasami a retrouvé une vie normale. Elle sort et va au lycée comme toutes les jeunes filles de son âge. Cependant, un rentrant chez elle un soir, elle trouve un DVD et décide de le regarder. Quelle n'est pas sa surprise lorsqu'elle découvre qu'elle a été filmée à son insu dans des lieux où elle n'a pas souvenir de s'être trouvé...
