According to Animate TV, an original TV anime "Boku no Imouto wa 'Osaka Okan'" was announced to start from December 21st. It's a 12-episode flash anime series and each episode is 5 minutes long.

Osaka Okan anime official website

Staff
Director & Scenario: Ishidate Kotaro ("gdgd Fairies")
Original Character Design: Sugahara Sota ("gdgd Fairies")
Production Studio: Charaction

Cast
Namika: Asumi Kana
Kyosuke: Shiraishi Ryoko
Kaede: Iguchi Yuka

Synopsis:
Kyosuke has been living apart from his younger sister Namika for ten years. One day, he begins to live with her, but she has turned into an energetic tsundere Osaka girl during the ten years.

Source: Animate TV

Boku no Imouto wa "Osaka Okan" on MAL