Kaibun (カイブン palindrome?) was a 2nd Year Student in Yabakune High School (矢場久根高校?). She was once known as Tsun (ツン?) and was a subordinate of Gekkou along with Rookie.
- Muto Tomu's name is a Kaibun (回文?), a form of japanese palindrome where the syllables can be read in reverse (mu-to-u-to-mu).
- Kaibun's actress, is also known to have a tsundere character.