Pick of the Litter

Pick of the Litter (異界繁盛記 ひよこや☆商店, Ikai Hanjōki - Hiyokoya Shōten) is a shōjo manga series written by Yuriko Suda that was serialized in Monthly Asuka from 2004 through 2007. The individual chapters were published in six tankōbon volumes by Kadokawa Shoten.

Plot
Five years ago, ten-year-old Riku Fukagawa arrived in Tokyo with no memory of his past except for his name. Since then, he has been living a normal life and going to school, while wondering who he really is and if he has any family still looking for him. One day, some strangely dressed characters insist that he is their long-lost relative and drag him to another world called Yamato.

There he discovers that he is "special," and that his family isn't completely human. They have animal like ears, animal tails, and special abilities. He has five older brothers who run a shop named Hiyokoya that sells weird objects like "live soap bubbles" and "tangle octopus." Thus begins Riku's adventure as he tries to study for exams in Japan and work at the Hiyokoya in Yamato at the same time.