Interview with Yagyū Koichi, 22nd Sōke of the Yagyū Shingan-ryū (柳生心眼流), which was one of the foundations of Ryōi Shintō-ryū.

Ryōi Shintō-ryū founder Fukuno Shichirouemon Masakatsu (福野七郎右衛門正勝) was a ‘ ‘Tatsujin’ (達人 – master expert) of the Yagyū Shinkage-ryū.

Yagyū Koichi, Sōke explains the difference between low kamae during the armoured Sengoku Jidai (continuous warfare) period and the higher kamae of the later Edo (1603 - 1868), when armour was no longer worn.

The same can be said for the transition from Sengoku Yoroi Kumiuchi (armoured grappling) to Edo period Jūjutsu.

See https://www.youtube.com/watch?v=F3nvreeZay4