Imouto no Oshigoto wa Jikyuu 2000-en

The "fake family" four-panel manga centers on a high school girl named Mieko. Lured by high salary, Mieko puts herself forward for a mysterious "little sister" job. Mieko's parents ran away at night when Mieko was in elementary school. She has lived with relatives ever since, but money usually runs out. However, Mieko is also worried about being left behind by her friends and the latest trends. This questionable "little sister" job becomes Mieko's lifeline.

(Source: ANN)