Reimu's one of those characters who starts out middling and becomes crazy-awesome later.
Believe it or not, she can actually be a better healer than Sanae, even if she learns her non-Bomb heal later! In fact, you max out her Barrier tree, suddenly her version of the piddly Ofuda of Healing is an AOE. In comparison, while Sanae gets her AOE healing earlier, Sanae absolutely MUST use a bomb to AOE heal - and Satori's learned ones are expensive.
Not to mention Reimu gets a complete set of Debuff removal spells very early...
That said, those 1-turn target all Bomb Barriers where she shines - the 2 I've learnt so far are pretty much Guaranteed No-Sells (vs Status and Damage respectively). With aforementioned maxed Barrier tree, they take precedence over almost anything! Alice Guard s the only other Guaranteed No-Sell spell, but it works only on Alice - and its a Last Word.
Low damage output? Fine - build her as the barrier mage she shoulda been!
- She has excellent RES. You can easily reach 100+ with only your weapon and armor, having all your accessory slots open for damage or defense, making her immune to all status. (4th tree has +40 RES) This makes her excellent at surviving attacks because you can use all 3 accessory slots for damage reduction items, while still being immune to all status.
If you're not far enough in leveling her yet, just put 3 points into her Concentration tree. Watch her shake Paralysis and Lethal Poison off at end of turn, VERY VERY OFTEN.
As for Nitori: she's all about the Chasers. You can do this before Stage 6:
1) Have Satori learn Flame and Frost, give'em to her. And maybe EM Wave, too.
2) Equip Patchy's all-hit Fire, Water and Wind attacks.
3) Build Nitori's Chaser tree until she has at least +1 Chaser Activation. Equip Fire, Ice and Thunder Chasers.
Laugh as Nitori hits EVERYTHING with a laced physical as your build-a-mages cast their all-hit elemental attacks - giving her like 2 attacks every time she casts a Chaser. Oh, and because it's partially physical, even enemies that don't take damage from the all-hit spells *take damage from the Chaser because it's a physical attack*.
For even more lulz, build her Chaser tree until she has 0 recovery for her Chasers, then build her Gun tree because those damage bonuses *are included in the Chaser activation*. And once Marisa learns her multitarget elemental spells, you can boost Nitori's Chaser tree further to get +2 Chaser Activation, and include HER in the fun. Its even useful against bosses that don't have a physical resist somewhat - just swap your build-a-mages into single-target elemental spells to save MP.
Nitori's other speciality is Elemental Physical Attacks. (She's the antithesis of Alice - Alice has Elemental Defends). She'll get a spell that laces her bullets with an elemental effect of your choice. Her Bomb attacks are STRONG elemental physicals that have the power of her Last Word at least. The only thing that can stop her? Physical resist. I still prefer using her as Chaser girl, tho.
