Oboro is good in general, but she's better for wave dps than bosses (but really good for hydra)

Kunoichi has leech which is sorta a knock-off budget heal, I built mine, but it was for sin city

Buangiri is fairly tanky himself, and has strengthen, but his shield for allies is pretty lame.

Consider Odachi (rare) if you have him. Tanky, hits decently hard, brings a team def buff and a 1-turn block debuffs

You could use Stoneskin gear to give yourself more hits.

It'd be nice to get Lydia before Argonites opens.

Masamoto does decent damage and brings Inc Def and Dec Atk.  Paired with Hotatsu you could keep both up all the the time.  I have both built for Sintranos.  

For the 5th spot, Burangiri gives Strengthen while Kunoichi offers Leech.  Leech might be better for your needs, but Hotatsu can palce that with his A1.  If you use Kunoichi, don't use her A3 or she will probbaly die.  On the other hand, Burangiri offers some usability for Bommal Progression, while I am not sure anyone uses Kunoichi for much else.   

Is this @hybrithe 

Nope, not me.

the name threw I guess.

Odachi is clutch bringing the block debuff for this boss.  Fenshi is a good option to TM drop the boss. 

I built my Odachi a very long time ago for a Cb speed tune to block the speed debuff if demon lord was spirit, and I've always been fond of him ever since. He's one of the few rares I think is totally worth maxing.

Funny story about him.  I had SK21 left to finish Lydia, no Odachi.  Said screw it imma pull 2k mystery shards trying for him (terrible idea).  Some miracle pulled him on the 3rd 10 pull.