a sea, an ocean / a lake / (figuratively) an object covering over a large area, as in 血の海 (chi no umi, “pool of blood”) or 火の海 (hi no umi, “sea of fire”)

inside

a raw, uncooked state / Short for 生ビール (“draft beer”).

thing (concrete, tangible) / (law) a corporeal object

dusk / twilight / livelihood / make a living / spend time

(archaic) to live; to exist

(archaic) to keep alive; to grow or raise

is the best among (others)

生: live; fresh; raw; natural

背中: one's back