The Miyake clan may not be very famous, but they definitely left their mark on Edo-Tokyo topography.
Most people seem to think the name Yotsuya is old. Old as in it pre-dates the Edo Period. But one thing that is consistent in most of the etymologies is the first kanji, 四 yottsu four. Much of the mystery of this place name seems to come from the final character. That said, the “number 4” character is also suspect. So let’s be skeptical, shall we?