Retail Therapy
Many shops in Japan sell traditional or culturally unique wares, which can be an interesting experience for travelers to have. They are also a popular place to find souvenirs to take back home. Unfortunately, in the case of this man, the entrance to the shop was a little on the smaller side. Maybe this is not an entirely bad thing- it would have been very easy for him to see the what was for sale on the top shelves, without even asking for help from staff.
The Metro is No Place for Tall Men
Rush hour in the metro is probably not a very pleasant experience when you are tall enough to reach the ceiling in parts of it. Japanese metro trains also tend to have advertisements hanging from the ceiling, which this man almost certainly would have run into many times while using the service. At least it makes for an impressive picture!