Mr Koike introduces Kemumaki Kemuzou - a new student at school. He appears to be a nice guy at first - but then becomes a monster after a love battle over Yumeko with Kenichi. Hattori has to stop him after Kemumaki cons Mrs Mitsuba.
Mr Koike is introducing a new student to class. His name is Kemumaki Kemuzou. Yumeko says he is really naughty, and she is proven right.
Kemumaki, Kenichi and the class are out at break. Kemumaki is sitting under a tree sewing a handkerchief. Kenichi talks to him briefly, and is impressed when Kemumaki catches a ball in mid - flight, but is jealous when Kemumaki gives Yumeko the handkerchief. Things get worse when the three of them go home together. Kemumaki uses his bag as a bridge for Yumeko to cross a puddle. Yumeko says goodbye to them - or rather, just Kemumaki. Kenichi is furious, and even more so when he is asked to push Kemumaki on the swings at the park. Kenichi lunges at Kemumaki, and is in trouble when Mr Koike passes by.
Things get even worse when Kemumaki comes with Kenichi to the Mitsuba house. Mrs Mitsuba is flattered by the boy's manners, which are fake. Enraged, Kenichi stalks off to his room and expresses his fury. Out of nowhere, Hattori pops up and tells Kenichi that they have to fight Kemumaki. They go to Mr and Mrs Mitsuba's room, where Kemumaki is. Kemumaki then sets a stinkbomb off and physically attacks Kenichi. Mrs Mitsuba is awakened from the ensuing rumpus and comes into the room, to find Kemumaki pretending to be injured. Mrs Mitsuba tells Hattori and Kenichi off. Kemumaki then pretends to plead with her not to grill her sons and pretends that he has no friends. Mrs Mitsuba is reduced to tears by this.
Next day, Hattori accompanies Kenichi to school. They meet Kemumaki in the corridors, where Kemumaki takes his casual outfit off and reveals that he is a ninja. Hattori and Kemumaki take part in their first duel, but run into Mr Koike, who tells Hattori and Kenichi off for creating a rumpus. He then finds Kemumaki's casual clothes, and says that they are his nephew's.
- Kanzo Hattori
- Kenichi Mitsuba
- Kemuzou Kemumaki (debut)
- Mrs Mitsuba
- Yumeko Kawai
- Mr Koike
- Mr Koike's nephew (mentioned)