On July 2nd, UNDERCOVER began selling a randoseru (school backpack) in collaboration with PORTER at the Re-Style Kids section on the 6th floor of the Isetan Shinjuku store. The brand's designer, Jun Takahashi, designed the colors, patterns, and materials for this randoseru. The base color is black, with blue accents on the mesh back and bottom. UNDERCOVER's iconic bear pattern is printed on the inside of the flap and the lining of the inner pocket. The name holder is embossed with the UNDERCOVER logo, and the side features the double name of both brands. The main material is PORTER's nylon fabric, with only the flap and bottom made of water-repellent cowhide leather. At approximately 1,100g, the randoseru weighs approximately 200g less than a regular randoseru. It is large enough to fit an A4 clear file. Priced at ¥71,280, the limited edition is limited to 30 units.

Regarding this collaboration, an Isetan representative commented, "Undercover has always focused on kids' clothing, but recently there has been a tendency to expand this line less, and we have received many requests from customers for more kids' items. When we introduced kids' items such as rompers and bibs in-store at Isetan in March of this year, the response from customers was good, so we approached Undercover and this collaboration became a reality."

The regular type of "Re-Style Kids x Porter" school bag, which is sold at the same venue every year, is scheduled to go on sale in August.