Konbini Yakin, Koe ga Dasenai Tenin (Imouto) ni!?

"The customers will notice, Onii-chan!" At the cashier, in the back room, in the fridge!? Naughty night shifts with my little sister.
(Source: Coolmic)
Note: Simultaneously released in long-strip format on mobile reading platforms, resulting in a total of 18 episodes being sold in 6 longer ones digitally.