This Airbnb is located ~15 min from the Shinjuku JR station and ~6 min to the closest Marunouchi Line station. The host provided directions that were easy to follow, and clear instructions on how to enter the Airbnb. There were no elevators in the building but getting the luggages up and down the stairs were not unmanageable.
There's also a FamilyMart and several other convenient stores nearby, plus some food places so you definitely won't go hungry.
The Airbnb itself was cozy and had what you need for a few night's stay.
Also appreciated how responsive the host was to my inquiries before and during my stay, and they did their best to address everything.