妹さんによろしくね。

younger sister

Mr.; Mrs.; Miss; Ms.; -san; makes words more polite (usu. in fixed expressions)

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

well; properly; suitably; best regards; please remember me; please treat me favorably (favourably); please take care of; just like ...; as though one were ...; by all means; of course

indicates emphasis, agreement, request for confirmation, etc.; is it so; hey; come on; listen; not