I'm also stuck here and I think there is a slight chance to beat her but it requires some rng. The way the fight works is that she will do one of 2 things:
1. attack with her light (15dmg) attack on the odd turns (so turn 1, 3, 5, etc)
2. attack with her heavy (22.5dmg) attack on the odd turns
I think the way to go is to get kanao as your companion and hope you get scenario 1 and always use your attack/MP regen skills on the 15dmg turns and block every other turn. This is because susamaru clone will ALWAYS use her ult and "lust attack" on turns 8 and 15 so you're pretty much forced beat her before that 15th turn. The reason for you wanting scenario 1 over scenario 2 is because that way when she does her first ultimate + lust combo you wont take as much damage and with the onigiris you might actually survive. Also scenario 1 gives you more chances to deal damage but even then it's stupidly hard and rng based. If you manage to make it work let me know and I hope this helps
Orion, it's impossible, she got scenario 01 after many attempts and used all the techniques that came before, but it's not possible, she always has 30/40/45 hp. I think I would have to use the thunder technique to reset the water skill at least a couple of times, then maybe we will be successful. However, I'm following the path of evil and soon after recruiting Susumaru I'm lost as to what I have to do next.