japanesecufflinks
kaikōsha club
kaikōsha cufflinks
made for kaikosha
manufactured for kaikosha
officer's club kaikōsha
officer's club kaikōsha cufflinks
偕行社製
偕行社調製
Set of obidome and cufflinks.
Made by Ikoma workshop.
Another such set https://asiamedals.info/threads/badges-marks-and-history-of-ikoma-workshop.20961/