Kojiro's Betrayal!?

Tortoise Europa
100px	aka Kumonga Z; Mecha Turtle operated by Kumo-Otoko; Fourth of the Four Heavenly Kings;

	Episode 15
	275px
	Information
Title:	Kojiro’s Betrayal!?
Japanese Title:	小次郎が裏切った！？ ; (Kojirō ga uragitta!?)
Original airdate:	July 16, 1993
Manga source:	Volume 6: Files 6-8 (055-057)
	Story
Cast:	Yaiba Kurogane ; Sayaka Mine ; Takeshi Onimaru ; Shonosuke ; Kagetora ; Musashi Miyamoto ; Gerozaimon Geroda ; Kojiro Sasaki ; Kumo-Otoko ; Ana Shioji ; Namako-Otoko ; Dorai Dorai ; Raizo Mine ; Shizuka Mine ; Sayaka's Grandmother ; Tortoise Europa
	Staff
Director:	Kunihiko Yuyama (chief) ; Norihiko Sudo
Screenplay:	Kenji Terada
Storyboard:	Akitaro Daichi
Episode director:	Akitaro Daichi ; Kazuya Murata (asst.)
Animation director:	Muneyoshi Fujita
Voice Cast:
	Minami Takayama as Yaiba Kurogane ; Kotono Mitsuishi as Sayaka Mine ; Ryo Horikawa as Takeshi Onimaru ; Masaharu Sato as Musashi Miyamoto ; Tetsuo Sakaguchi as Kumo-Otoko ; Jurota Kosugi as Kojiro Sasaki ; Kazunari Tanaka as Gerozaimon Geroda ; Tsutomu Kashiwakura as Namako-Otoko ; Mami Matsui as Ana Shioji ; Tessho Genda as Dorai Dorai
	Music
Opening song:	Yūki ga Areba
Closing song:	Shinchigakunaki Tatakai
	Chronology
Prev episode:	« Vanished? The Enemy Chameleon
Next episode:	The Strongest Machine of the Four Guardians Attacks! »
	List of episodes

Characters introduced

Characters

While introducing himself to Dorai Dorai, Yaiba recites the first eight decimals of the Square root of 2 (1.41421356) and the first seven of the Square root of 5 (2.2360679), which has to be remembered by all Japanese students. The fact that they have to remember the first digits of a square root is also shown in The Marriage Registration's Password.