Mr Koike tries desperately to stop Kenichi from becoming the school's new marching bandleader.
At band practice, Mr Koike, the science and calligraphy teacher, and Miss Aiko, the music teacher, are supervising the recorder band during rehearsal. The lesson ends, and Miss Aiko asks the students to tidy up as an after-school job.
About five minutes later, amid the tired grumbling of the students, Kenichi Mitsuba rushes towards the bathroom, desperately needing to pee. Knocking over Kemumaki and Yumeko, he makes it to his cubicle, but as he finishes, he overhears Mr Koike and Kemumaki having a civil argument about choosing the new bandleader. "Mr Koike", who, in reality, is Kemumaki doing a voice-over, considers choosing Kenichi, while Kemumaki who is pretending to reply in his own voice, is opposing Kenichi's selection. Kenichi is motivated to a great degree, but his eyes fill with an angry fire as he thinks of Kemumaki.
Back at home, Hattori praises Kenichi and vows to support him, while Mrs Mitsuba breaks down in tears of joy and tells her son that he will be the first ever Mitsuba to be a school bandleader. Mr Mitsuba, slightly teary-eyed himself, gently tells his wife to get a grip, then tells Kenichi to do his best and wishes him luck. Shinzo asks his brother if being a bandleader is tricky, and Hattori tells him that even though it isn't hard, it's a big responsibility. Kenichi vows to put his heart and soul to the task, and immediately promises to rehearse.
Later on, Kenichi organises an impromptu parade with the whole family taking part: Kenichi, of course, at the head of the party, Mr Mitsuba playing a bass drum, Shinzo clanging some cymbals, Hattori playing a side drum, Mrs Mitsuba a recorder, and Shishimaru a harmonica. After a round around the house, Hattori senses Kemumaki and Kagechiyo spying on them and taunting Kenichi's parade. Hattori returns to the house and gets told off by Kenichi for wasting time. Hattori summons him to the living room, and he asks who informed him of becoming the bandleader. Kenichi replies that Mr Koike and Kemumaki were conversing about him becoming the bandleader, and that he just overheard them. Hattori, excusing himself, goes to Mr Koike's flat.
At the flat, Hattori goes into hiding. He watches Mr Koike prepare a dart board so that he can choose the bandleader, and even though it has Kenichi's name on it, he has no intentions of proclaiming him as the bandleader. Hattori realises it was all a trick, and opts to use his ninja techniques to make Mr Koike choose Kenichi. Using a small rubber ball, he sends the dart towards Kenichi's name on the board. When the dart hits Kenichi's name, Mr Koike laughs derisively. After a few more attempts, the remaining darts hit Kenichi's name. Mr Koike uses a dice to decide the band leader. He puts Kenichi's name into one of the numbers, and every time he gets a number, Hattori adds more black spots to choose Kenichi - which results in Mr Koike "choosing" Kenichi. Sick and tired, Mr Koike goes to bed - but he has a nightmare which shows about five Kenichi's marching towards him with drums. Realising that there's no option left, Mr Koike selects Kenichi.
Next morning, Mr Koike tells Miss Aiko about his decision, and Miss Aiko also considers Kenichi. Kenichi is delighted, but Kemumaki is fuming, and knows that Yumeko will be pleased when she finds out. Hattori, who has been spying on them, says that Yumeko, as a friend, really will be pleased.