Wakai (written: 若井) is a Japanese surname. Notable people with the surname include:
, Japanese karateka Glenn Wakai (born 1967), American politician , Japanese footballer Atsuko Wakai (若井 敦子, Wakai Atsuko, born 1971) Japanese practitioner Wakai ki (若い樹) (lit. 'A Young Tree') Japanese film directed
See also Wakai Station, a railway station in Kōchi Prefecture, Japan