Any one got any information about Gyokurin?

1.9 i recently finished restoring by Gyokurin.
Urushi coated rattan bindings and some bore work.

it had a silver nakatsugi rings and either silver or steel pins holding an old crack at the root.

My guess this flute is around 50-90 years old.
the sound is soft and tender, perfect tuning other then a sharp chi which along with the dark color of the bamboo, makes me think its old (old tuning).
the color of the bamboo is very dark and there are markings and worn holes which seems that someone played this flute a lot in the past....


But actually i know nothing about the maker. can anyone shed some light on the mystery for me?






bottom pic came out upside down for some reason. sorry.