I was either in Tokyo for the day or teaching in my room so our communication was limited for ten days, but Keita's place is perfect value. I could always get into Shinjuku or Shibuya within 40-45 minutes as advertised.
I teach ESL live lessons online, and the space is perfect for it.
Yes, the overall place may make you feel a little claustrophobic at times, but that didn't bother me at all.
Keita has a very organized list of instructions and is super friendly.
Be aware last train back to his place from Shinjuku or Shibuya is roughly 12:30am. You may have to walk from one station away at night if you are between 12:30-1am. I had to make the late night walk twice lol. And no trains run after 1am from Tokyo. So if you are a regular night owl, take this into consideration before booking.
Otherwise, book with Keita!