It's Thursday (木曜日: mokuyōbi) here in Japan and since 木星 is Jupiter, the Japanese "Thursday" seemed to align more with the French "jeudi", but remembering Jupiter was partial to thunderbolts and thus equating to Thor solved the puzzle.
https://en.wikipedia.org/wiki/Thursday
What was harder to resolve is "Wednesday", but apparently OED suggested both Odin and Mercury were "gods of eloquence" (and 水星 is the planet Mercury, hence 水曜日). Interestingly "mittwoch" sidestepped all this.🙂
https://www.etymonline.com/word/Wednesday