As far as isekai goes, this one is pretty alright! It's a slice of life one with some light back-story but the characters and their interactions are a nice change of pace from most similar settings. Nothing unique, but well executed. Overall a nice read that manages to not fall flat on its face; it's also a double-isekai (otherworld-otherworld) so it avoids many of the pitfalls of an MC with modern knowledge.
Not entirely sure where the ecchi tag comes from; there's some monster-girls/demons in lingerie-armor and buff male centaurs without clothes that might qualify, I guess; also a few panels with a seductress type character in revealing clothes but it's not more than some under-boob. Oh, and a single panel with some non-gratuitous and mild nudity (transformation). That's about it -- no pantsu or fluttering short skirts or disintegrating clothes or onsen or getting dressed; there's some implied sex between husband and wife (but nothing shown) which could only raise eyebrows from the most purist of puritans. Honestly, Sailor Moon is more risque than this one!
EDIT: I said all that and a month later there's an onsen episode coming .... Well, I guess that's to be expected.