Found on a back street.
BEEP Akihabara" will open in mid-September.
It is located on the B1F of the building next to Whatcan, where Jampara Akihabara No. 3 is located, on the former site of the hobby store " Treasure Hunter" ( September 2011 - July 2014).
The shop handles retro PCs, retro games, arcade circuit boards, and doujin goods, and it also appears to be a buyer.
Business hours are from 11:00 to 20:00. Closed on Wednesdays and Thursdays. The store is currently preparing to open during Silver Week.
[Addition.]
Added image. The opening is scheduled for October 2.