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
Director & Scenario: Ishidate Kotaro ("gdgd Fairies
Original Character Design: Sugahara Sota ("gdgd Fairies
Production Studio: Charaction
Namika: Asumi Kana
Kyosuke: Shiraishi Ryoko
Kaede: Iguchi Yuka
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"