Hakke-an is, simply put, a fantastic place to explore Tokyo from.
The apartment itself is small, (perfect for one, maybe a squeeze for 2), and has a nice living space / single room, a modern toilet / shower room, a separate sink and a small kitchen area to make tea from. It also has good WiFi and plenty of charging sockets. The ceiling in the main room is low, so be careful when changing!
The nearest subway is 2mins walk away and is at the start of one of the main lines (Chiyoda line). If you prefer to stretch your legs It's a 20-25min walk into Shibuya.
There are some nice places to eat in the area: 15C is a great breakfast option and Crossroads is a great takeaway coffee place around the corner. And the bar downstairs, run by Minmin, is welcoming and relaxing. I personally had a great time in the bar and would recommend popping down to say hi.
And finally, Daisuke is a great host. He quickly replied to my questions and offered up some great tips to explore in Tokyo. Thank you Daisuke for being so awesome - and hope to meet you sometime in the future.