LOSSBOUT 01 · VS Zenitsu Agatsuma
In the Infinity Castle, Kaigaku batters Zenitsu with electrified black Thunder Breathing forms, but Zenitsu unleashes his personal Seventh Form: Honoikazuchi no Kami, blitzing Kaigaku and decapitating him in a single blinding strike.
FILING NOTE
Files L because Zenitsu Agatsuma unleashes his original Seventh Form and decapitates Kaigaku in a decisive one-on-one duel.
WINBOUT 05 · VS Kaigaku
In the Infinity Castle Zenitsu faces his former senior Kaigaku, now Upper Rank Six, and is beaten down by Kaigaku's Blood Demon-charged Thunder Breathing before he uses his own seventh form to behead him.
FILING NOTE
The fight begins in Chapter 144 and Zenitsu beheads Kaigaku in Chapter 145, where it resolves, while Chapter 146 shows only the fall and the rescue. The first Infinity Castle film adapts chapters 140 to 157, so the episode is IC-1.