A high school boy named Haru and his mother are living overseas. His mother orders him to take care of and "civilize" his adoptive brother Ren, a wild young boy who dislikes talking with other people. While their relationship is adversarial at first, they grow closer as they begin to understand one another.
 
(Source: Anime News Network)

While spending summer with his mother, Haru meets Ren, a boy newly adopted by his mother. Getting along with Ren isn't easy as Haru's goal is to "civilize" him by the time summer ends. Their relationship slowly improves as Haru spends more time with Ren and in return Ren steadily warms up to him. Can they really become a "family" at the end of summer!? 

(Source: Kadokawa, translated)

After leaving Canada to move in with Haru, Rei was finally getting used to living as the youngest of four brothers, and Haru's new café was beginning to thrive... when their mother, Haruko, showed up and said she was taking Rei with her to Switzerland! The shock of her sudden declaration just when Haru and Rei had begun to grow closer led to increasing discord between them. Is more trouble on the horizon?!
 
(Source: Crunchyroll)

Bundled with manga's tenth and eleventh volume.

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