Seiya's apartment is located very close to Takadanobaba station, which is on JR Yamanote line, so it's very easy to get around the city. There are lots of restaurants in the area, some very good ramen too. And there are convenience stores and drugstores nearby so you have everything you need.
The apartment is not big, just like apartments in Tokyo do, but it has everything: a small kitchen, toilet, wardrobe and futons for sleeping, and even a balcony. So you can experience an authentic Toyko living style.
Seiya is quick to respond to messages and always checking in to make sure everything is ok.
A side note is that you have to climb 3 stories of stairs (the apartment is on the 4th floor). But the route from the subway station to the apartment is smooth, and there are elevators from the train platform to the ground floor so it's not too bad if you have heavy suitcases.
As sometimes hostel dorm and capsule hotel can cost almost as much as this entire apartment. Here it is good value for money, I'll recommend staying in Seiya's place!