Dictionary/私書箱ししょばこShishobako私書箱 (Shishobako) is a Japanese noun meaning “post office box”.Meaningsnounpost office boxKanji in 私書箱私private書write箱boxRelated words私I私I書くto write私たちwe文letter箱box私邸private residence私用personal use秘書(private) secretary書類document私的private報告書(written) report