Very much enjoyed the stay at Serina's house! The room was spacious, with a desk and (somewhat hard, but I like that) bed, located on the top (2nd) floor of a typical Tokyo single family house in a residential neighbourhood. The room and the shared spaces were clean, and everything was in great working order; the corridor with the stairs being somewhat tight on space (Tokyo, after all).
Ikebukoro station is only a small number of stops away, with two metro stops close(-ish) to the appartment: Naka-itabashi (a bit further, but many shops, restaurants around it), and Itabashihoncho (very close, but not much around except for 7-11 convenience store).
Serina is a very friendly host with a bubbly personality; we ended up talking lots about travel over a cup of tea. She also picked me up when I could not quite find her house, thanks to the somewhat strange house and street numbering scheme (and Google Maps not knowing) -- you should definitely check with Serina where the house is actually located before you arrive.
Overall, highly recommended, if you want a quiet, friendly, homely place to stay!