Sumiko Iwamuro knows a thing or two about juggling work.

She spends her days behind the counter at a family-run specialty gyoza restaurant and one or two nights a month moonlighting under her stage name DJ Sumirock. It is an impressive feat for someone 82 years old, although she insists otherwise.

At 2 a.m. when other octogenarians are fast asleep, Iwamuro — donning her trademark sunglasses and bright red lipstick — is spinning beats to the delight of the crowd at a dance club in Kabukicho, the famous red-light area in Tokyo's Shinjuku district.