This is the Reflection of Strength, unlocked after killing him in the Gauntlet.

Inner Isshin is not too different from the normal Sword Saint Isshin, so personally I think he is not hard to defeat, but doing no damage did provide some challenge. This run had moments where I was less aggressive because in previous attempts, I was way more aggressive but got caught off guard by his quick retaliation sometimes, taking damage near the end of the run.

I'm not a pro player so my combat style is very basic, without much creativity and fancy moves. Only using basic deflects, jumps and mikiri counters etc. But I do play with no kuro's charm aka charmless mode, so I guess its an achievement somewhat.

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