Grimoire 2 Mangapage

It feels strange for your characters to use 私 and あなた. In manga that's polite speech for the more quiet types. The boys should use 俺 or 僕 to refer to themselves (darker haired one is definitely an 俺) and 君 or お前 or similar to refer to the listener. And the girl is a bit too tomboyish for the polite speech too. I suggest using あたし for "I" and あんた for "you".

Grammar is not bad at all, but the way the sentences are formulated are unnatural. Especially in their context and character. For example, I would replace あなたはまだ生きている、少なくとも with お前にはまだ命ぐらいはあるんだな, or something else depending on the exact context. And マイケあなたは私をつぶす is very awkward. I would make it something like マ、マイケ・・・息が苦しいっ, which means "Ma, Maik... I can't breathe". Even then I would ask some people for a second opinion, because I'm not confident about my Japanese skills when it comes to this.

But the illustrations are very good! They are pretty much indistinguishable from professional Japanese stuff. If someone would tell me this was actually printed in Japan, I would have believed it (before reading the text )