A story set sometime between Mosquito Girl's defeat and Genos showing up to Saitama's apartment. Genos wants to learn the secret to Saitama's power and decides to follow him and to observe everything he does. At the same time, Saitama is convinced that someone is stalking him.
Elenco: Makoto Furukawa , Kaito Ishikawa , Kazuhiro Yamaji , Yuichi Nakamura , Kenjirou Tsuda , Aoi Yuki , Minami Takayama , Hiroki Yasumoto , Takahiro Sakurai , Youji Ueda , Daisuke Namikawa , Satoshi Hino , Yuji Ueda , Kohsuke Toriumi , Katsuyuki Konishi , Hatano Wataru , Masaya Onosaka , Mamoru Miyano , Saori Hayami , Yuuki Kaji , Tesshou Genda , Hikaru Midorikawa .