4-5 hours of free time after Haneda Airport

Hello,

My brother and I are planning on meeting up at Haneda airport for a 1 week trip around japan. We both arrive on May 25th, but I will arrive earlier at 4pm and he will arrive at 9pm. After I arrive I will be going thru customs/ getting an IC card / picking up pocket wifi and after that, I am not sure what to do until he arrives.

I am looking for suggestions as to what I can do in the 4-5ish hours I have before he arrives and we meet up at the hotel. I am an anime/gaming fan and he is not as much, so I was thinking of swinging by Akihabara, putting my luggage in a coin locker and checking the area out since I don't think he would like to spend as much time as I would there. I was also wondering if it would be a good idea to check Yokohama out but not sure if thats a good idea or not. I am open for suggestions.

Our hotel is in Shinjuku for context.

Thanks!

Haneda Airport to Akihabara, 36 min 690 yen.
Akihabara to Shinjuku, 18 min, 180 yen.

Haneda Airport to Yokohama, 35 min 370 yen.
Yokohama to Shinjuku, 35 min, 580 yen.

Note that you must take some time to see in Yokohama since Yokohama station is not in the center of tourism.

You may better go to Akihabara if that is your preference.