English let's

← German [[lass]] [[uns]] (speaker with one other person) / [[lasst]] uns (speaker with more other persons) (cognate)

← English let us (contraction of)

← Dutch [[laat]] [[ons]] (cognate)

← Swedish [[låt]] [[oss]] (cognate)

→ English be (link)

→ English be (link)

→ English us (mention)

→ English -'s (link)

→ Japanese レッツ (borrowed)