Oni Buchou ga Imouto ni Nattara: Gap Arisugi Amaenbou

Office worker Yugo's boss, Kanade, can be demanding and runs a tight ship around the office. However, One day, Yugo and Kanade's parents remarry, and the two become brother and sister?! Without knowing what to expect with his little sister as his boss, Yugo receives a sudden important task from Kanade; "hug closely for 30 minutes." With all the control in Kanade's hands, poor office worker Yugo must now navigate forbidden feelings of love while adjusting to the power balance with his devilishly lovely little sister boss!

(Source: Coolmic)

Note: Simultaneously released in long-strip and traditional formats, with 18 episodes and 6 chapters respectively.