Battle One: Moibini

Reward: Anti-Demon Seal x5

Use Poison and Dragon Water Cannon, and heal yourself when needed.

Battle Two: Soldier x3

Reward: Mist Sword Guard

These guys can do some serious damage, and they take a long time to kill. Fortunately, they’re susceptible to Sleep and Poison.

Use these two skills repeatedly to kill the soldiers without having to attack. (Literally, just keep cycling between Sleep and Poison until they're all dead. It will take a long time, but all three of them will die, and Karin will rarely sustain any damage.)

Battle Three: Raider

Reward: Void Lv6

First, use Heat Haze. This will help you to evade his attacks.

Then use Poison if you want to, and then four Funeral Flames. (But use Heat Haze again any time it wears off.) If you take damage, you’ll probably want to use a Lucklau; otherwise there’s a good chance you’ll die on the next turn.

If you run out of Funeral Flames and he's still alive, you can use Dragon Water Cannon (on turns that you're not healing). As long as you don't run out of Lucklau, you can win this battle.