Not even level 150? Shin's ex-gf is a casual player confirmed. She probably played the game more for the social features. She does have more friends in-game than he does. She didn't try to use this adventure as a chance to power level or something, and was really just there to go sightseeing with Shin. But it's fine. Not everyone has to be a hardcore gamer to enjoy something, and they weren't in a difficult dungeon where everyone needed to pull their weight.
Hibineko and Shadow looked positively strong here, and even then they were one of those who died in-game. Come to think of it, Shin is the only one in that party who didn't die. Yes, I'm assuming Marino died too since that outcome makes the events surrounding Shin make more sense.
For some reason Cashmere's design does not surprise me at all. She looks like a sunny, gentle and seiso-type character, and she won't even look weird if you added some sheep horns to her design.