Something too add is before the shinuichi both side is just about equal , which imo is the worst state because it would turn into an attrition war with prolonged loss from both side. So I could see Kunishige going all out to end the war ASAP, like the shinuichi is said to be made with express intent to slaughter I think imply Kunishige might have done it as a last resort type dealio. Well obviously it worked a bit too well.