Скачать или смотреть Lost Judgment [The Kaito Files] - Secret Boss: Blood-Drunk Master

After defeating the three optional bosses that spawn by wearing the Bloody Crest and learning every other skill, you'll unlock the Letter of Challenge giving you access to the secret boss of the Kaito Files. That means there's no way to fight him without maxed out Attack power.
Once you've unlocked the skill, get to the elevator in the Kamuro Theater and the battle will start as soon as you take it to the ruff.

The Blood-Drunk Master uses Tesso's fighting style and has ten health bars, but with maxed-out Attack, Kaito deals so much damage it won't feel like it provided you manage to get some good hits in. Be prepared to deal with Bleeding, and when your opponent backflips, be ready for his throwing knives.

Aside from that there's not a lot to say, stick to short combos and use EX Mode for increased damage on EX Actions if you really want to deal out massive damage, it's not a very difficult fight and it awards the final trophy/achievement for the DLC!

You can talk to your opponent after winning, and he'll mention "his clan", but what could that possibly mean...?