I feel like that oyakodon explanation should be changed, unless it actually just says egg on rice (which oyakodon isn't), then I don't really care much
Really, I was expecting this to be like Nidome no Yuusha but no, this is just him going around getting revenge with no cost just because, I mean there is a sense of satisfaction but not that much since we don't really revel in the "depth" of his experience and what the targets did, in my opinion...
Don't try to be a nice poopy person you dumbass MC, some people will just take advantage of your naivety and kindness and repay with the bad stuff, so just repay them with what they do to you, easy and simple
Where have I heard of this plot before, child of two persons not together yet came from future to get the two together, I can't remember where I've read or heard of a similar plot, but I most certainly remember reading/hearing about it