MC is dumb and made dumb decision, but he is not a bad guy. mizuhara know, even she is annoying tsun, she know this herself the best. mami is just bitch being bitch. and as usual being prejudice by calling MC using mizuhara for his greed. while she isn't complitely wrong, main purpose of MC is still her grandma. he never purposefully bring her to blasting off in front of his friends. in the beach it was coincidental (MC is the one has plan first before mizuhara with her friends), even now, it was mizuhara that coming (probably purposefully) to place where our MC works. rukia is too innocent for her own good, might do some dumb decission but definitely not a bad girl either.