My group of 3 was really really happy that we chose Seijis apartment. It is spacy enough for 3 adults, it has everything you need. WiFi in apartment, portable WiFi to navigate through Tokyo/Japan, dishes, umbrellas, big refrigerator and everything near! 2 Family Marts in 1 1/2 minute walk, 7 Eleven in 2 minutes, 100 yen store in 1 1/2 minute, many restaurants around..
The San-Chome station was also more useful than we thought, super awesome to get around from there; but for Marunochi line we recommend Shinjuku Gyoenmae station!
Seiji was also an awesome host. He was replying so fast to our not quite few questions, and so accurate! It was insane. He is also a really nice person to meet! :-)
Overall we would love it to stay in his apartment again!!