[Beginner's Tutorial] Warning: Your companions are not bullet-hell shooting machines.

In this game, each character has a 'mood' stat. You can find the character's mood icon in the picture. When you take them into battle, this mood stat gradually decreases, (it decreases even more significantly if they become incapacitated), and eventually, they'll start struggling and sweating. When the icon changes to a sweat droplet, you should let them rest instead of taking them into battle. If it changes to 2 sweat droplets, you should definitely let them rest. 2 sweat droplets mean they're in a 'can't push it any further' state. If you continue fighting in this state, their affection will decrease. Since affection is linked to a character's combat stats, it's generally better not to overexert them. There's no way to recover mood other than letting them rest. Placing characters in the 'Academy' speeds up mood recovery. Also, characters placed in the 'Academy' can become much happier than usual (2 stars), and fighting while in this state increases the EXP you gain.