(LEAD) Rain says 'Please Come Back, Mister' will speak to have-nots

(ATTN: UPDATES throughout with details) By Park Sojung SEOUL, Feb. 19 (Yonhap) -- Singer Rain says drama "Please Come Back, Mister" is a story about all the have-nots in society. The 33-year-old heartthrob plays Lee Hae-jun, a handsome department