Ok, I know I've written about Hayato a few times already in the past, but I really, really believe that he's rather underpowered. He is, in essence, a fast-paced mobbing warrior. However, that seems to be the only thing to him. His 1v1 skill, Shinsoku, seems rather underwhelming, even with Hypers considered and even a decent bit of funding. Moreover, his playstyle seems to be lone-wolf like, but he doesn't seem to be fully equipped for it. In particular, he has no bind, silence/seal, or the like to counter things like Damage Reflect and Cancel Physical Damage. This endangers him at worst, hinders him greatly at least for most major bosses (Empress, Hard Magnus, to name 2).
Aside from that, I believe that Hayato, for it's current underpowered status, is rather hard to buff with out becoming overpowered. It's already kind of a bully class early to mid game (Lv. 30-130) in terms KSing potential because of his mobbing abilities, plus his blisteringly fast attacks. If one were to adjust the damage %'s of his Sanrenzan, or even add additional attack lines, it makes him overpowered. Perhaps if Shinsoku had a higher % damage per line, it can help things, but I would suggest adding a bind of some sort to his kit.
Now, skills aside, I also believe that there is an even greater reason he doesn't get as much love from players: his mastery. Granted, he has 60% mastery from the very beginning, but that would be it. Other classes get 80% mastery, keeping their damage relatively stable. Hayato? His damage jumps around as much as he does. There is also the matter of his attack multiplier (which is very hard to adjust in a way that is balanced). To summarize this, Hayato's Katana is considered 2h, but has a multiplier more indicative of a 1h weapon. Katana have a multiplier of 1.25, compared to a general multiplier of 1.2 for 1h swords, maces and axes. 2h swords/axes/maces have a general multiplier of 1.34, and spears/polearms have 1.49.
With the above in mind, what, praytell, do you guys think would balance Hayato out?