Yep, not suspicious at all. You should totally trust what someone says someone else said, especially with something as important as this.
Life lessons:
Trust but verify
Get everything in writing
Yeah, but that’s in the WN. Nothing like that is shown here. I agree, he’s being too merciful in the manga version, makes it feel like there’s no stakes or consequences to the bad guys’ actions. Which makes MC feel like too much of a goody two-shoes and kinda boring and morally weak
So basically the same as every other generic Japanese isekai protagonist…
Being merciful just to “be a good person” or whatever isn’t being virtuous. It comes off as being weak, cowardly, and pathetic
Lol Mahiro indirectly calling Asahi an idiot at the end there
(“Even Asahi gets them,” indicating surprise that she caught a cold. If you didn’t know, in Japan, they have a saying that idiots don’t catch colds.)