Hina

Hina is an event unit with strong physical and magic defense that is bolstered further when she is surrounded by party members. Her unit skill is a damage reduction passive that cuts down her damage received based on the formula of 1 / [1 + (# of units besides Hina) x 0.1)]. As of update V1.04, this even includes enemy units in the consideration of the damage reduction formula.  When it comes to her level growth, she is moderately slow, but not as slow as units such as Remilia or Tenshi.

Where to Obtain
Hina and her spell cards can be acquired from the Event Quest "Hina Attacks," which is open to units level 5 and above on Easy difficulty.

Strategy
Hina is a tough unit with strong physical and magical defense, but since she does not attract damage like Meiling does, it is hard for her to assume a similar tank role to Meiling's. Because of her high defense, however, she doesn't require much protection or healing from outside sources. Bad Fortune's passive effect applies to the entire allied party, so it can be a helpful card to use against units that cast negative status effects, such as Rumia, Cirno, and Medicine. Broken Amulet can help fellow magician party members with strong magical attacks, so it has high compatibility with units like Patchouli and Marisa. Pain Flow is a strong spell card that essentially forces the enemy team to have bad luck every time they draw a strong spell card. Every time a strong spell card with a high bomb cost is drawn, Pain Flow will subtract an equal amount of bombs, making it much harder for the spell card to be used, as well as being able to prevent lower cost spell cards from being used. Pain Flow also has high synergy potential with Sakuya's Eternal Meek, as Eternal Meek also subtracts bombs based on its successful amount of hits. Together, Hina and Sakuya can effectively strip the enemy team of bombs, making it difficult for new spell cards to be cast on the opposing side.