Page 2 (chapter page 1) field 2: "It's crowded in here" reads weird - it's an outdoor arena and it's not crowded around him. "Such a huge crowd..." or something to the effect of the seating being packed feels more natural.
p4f2: Either "let's HAVE a warm welcome FOR" or "let's GIVE a warm welcome TO" would be correct
p5f2: "will everyones after this," you've said here in the comments should be "Will everyone be meeting up after this?"
p6f3: "I'll go on ahead" reads better
p7f2: Even if he can't WHAT, will he try? This needs to be rephrased. I don't know what he was going for, but I assume "Even if I fall short, I'll still do my best."
p7f3: "What's with the sudden kindness?" instead
p7f4: This feels stiff and weird. "I'm glad to be a player, thanks to you."
p7f5: "since I've felt so alive" would be correct.
p7f7: Excessively formal, even if the Japanese is, too. Please punctuate.
p7f8: "congratulations on your victory" would be correct.
p7f9: "thank you a bunch, too" is weird, "thanks a bunch" is more natural if you HAVE to phrase it that way
p11f1/5: two fields starting "And so" is rough unless there's a good reason.
p12f2: "sorry for the wait" and "we arrived at Morioka..." seem switched, as you've noticed, but haven't fixed
p13f1: "I got a good night's sleep..." or "I slept well last night..."
p13f2: should be "let's do this" as noted
p13f5: "spikes of level increase" is weirdly phrased, "reports of the monsters' levels in this dungeon suddenly spiking" or something would make it more clear
p13f6: "which is unprecedented" if you're continuing the previous sentence, "it's unprecedented" if not, either way should be a separate sentence if you're trying to keep the phrasing as close to that as possible. We can't tell, because there's no punctuation. "there were some monsters that WERE even stronger than those..." would be correct.
p14f5: "similar to a human's," "even THOUGH you called"
p14f8: "SHUT UP."
p14f11: This joke doesn't translate, whatever it happens to be. Localize it to an equivalent joke, or include a note explaining the original pun or whatever it was.
p15f2: "Those things ARE huge!"