I highly recommend Dong's place as it is very accessible. It's in the middle of Koreatown and Kabukicho. 3 train stations are also within walking distance, but it still might be a bit of a hassle to walk to and from the apartment if you have big luggages. A Donki store, which is open 24 hours, is just right beside our place. Several Korean restaurants and conbinis are within reach.
Check-in was a breeze since Dong sent instructions with pictures. I love how he's easy to talk to since he speaks English. He allowed us to check-in earlier since we arrived Tokyo in the morning and there were no guests before us. As for the room itself, it's clean and sufficient. Beds are comfortable to sleep in after a long day of walking. Basic appliances are provided for. The bathroom has everything you need. Considering Tokyo's standards, space is big enough as we are able to open our luggages in the main room and still walk around. Take note that we are Asians, so this may not be true for everyone.