In retrospective I realize why the artist made the mice pardon Ichirin: she has no background other than Unzan. The mice attacked the girls based on the info we have about them (Shou losing things, Murasa sinking, Hijiri being a devout), but Ichirin only has, well, that he met Unzan, no trauma nor weakness to exploit.
fluff-fluffBastard, you're one of the rebels, aren't you!?No objections!But Kumoi Ichirin is is close to Unzan, the nyuudou!No. That's a misunderstanding!...is terribly unfortunate!Wait, platoon leader!I'd like to request a delay of our revenge towards Kumoi Ichirin!Losing the pleasure to nap on top of his fluffy back is...All in favor of pardoning Kumoi Ichirin!No objections!*squeak*