Where does “ボイシ” come from?

ボイシ (Japanese) comes from English Boise, from French [[la]] [[rivière]] '''[[boisé]]e'''.

Ancestry of “ボイシ”, step by step

Step	Language	Word	Meaning
1	English	Boise	—
2	French	[[la]] [[rivière]] '''[[boisé]]e'''	—

ボイシ — Etymology, Origin & Word History | Etymology Explorer