The Japanese international is part of the squad that will fly out tomorrow for matches in Indonesia, Vietnam and Nagoya in Japan.
The 22-year-old told the club's website: "It is my city, so it is exciting to return. As an Arsenal player I'm coming home, so it is a great moment for me. I'm very proud.
"At the end of the season I was there for a month. It is not too big, it is maybe the fourth or fifth biggest city in Japan, and it's quiet and has a lot of traditional things there. There's good food and it's a great city.
"It is quite a good moment for me and I want to show my quality for everyone in Japan. Japan is my country so I'm really looking forward to going there. I'm very happy about it."
Miyaichi played four games during a loan spell with Wigan Athletic last season.