彼は歌を歌いながらやって来た。

he; him; his; boyfriend

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

song; classical Japanese poetry (esp. tanka); modern poetry

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to sing; to sing (one's praises in a poem, etc.); to compose a poem; to recite a poem

while; during; as; while; although; though; despite; in spite of; notwithstanding; all; both; as (e.g. "as always", "as long ago"); in (e.g. "in tears")

to come along; to come around; to turn up; to arrive at the present; to get where one is; to have been doing something (for a period of time)