What should I invest Focus Points into? Ideal for ninjutsu build?

Just reached 750 max level and got a notice about the focus level feature. Since focus is irreversible I'm hesitant to allocate any points as yet. Any suggestions particularly for a ninjutsu build?

Kind of a side question but I'm still in the process of farming gear for ninjutsu build. There's a lot of possibilities, so if anyone has their favorites to take on the underworld it'd be greatly appreciated (eg - set bonuses, particular gear pieces, particular gear stats, anima types and stats, etc).

Any advice at all is greatly appreciated as this is a complex game especially when it comes to customizing and perfecting builds!

TL;DR: Focus points for a ninjutsu build? Any ideas for ninjutsu gear and anima? Thanks!