sentences:  Six pieces of theme music were used for the series.For the first 23 episodes, "Red Fraction" by Mell serves as opening theme, and "Don't Look Behind" by Edison is used as closing theme, except for the fifteenth episode, which features "The World of Midnight" by Minako Obata.Episode twenty-four lacks an opening theme and uses "Peach Headz Addiction" by Breath Frequency as closing theme.