The Translation follows;

此狀者名五早乙女家久士作也
昔藩主天休院源運貞賜之于其
老臣長坂某々家代々秘藏經星
霜二百餘年傳至子孫弘敬今弁
有故將交之于骨董之手余悶之
愛惜不捨遂投贈金購之為作置
以永久期名器之不沒滅因叙其由
來遠論後代云爾
明治三十有二年秋九月
廉識

This helmet is the work of the renowned artisan Saotome Iehisa (circa 1600AD).
In the past, the feudal lord Matsudaira Harusato of the Matsue Domain bestowed it upon his loyal retainer, Nagasaka.
It was carefully treasured by the Nagasaka family through the generations for more than two hundred years.
It has now come into the possession of his descendant Hirotaka.
Due to unavoidable circumstances, he was about to entrust it to the hands of an antique dealer.
Upon hearing of this, I could not bear the thought, and with great affection, I purchased it for a considerable sum.
I have made a case to preserve it, hoping that this celebrated piece will never fall into obscurity.
Therefore, I record its provenance for the benefit of future generations.

Autumn, September, Meiji 32 (1899)
Signed: Renshiki

To sumarize the Daimyo Matsudaira Harusato had given this as a gift to his retainer, it was passed down in his family and later sold in Meiji period due to personal reasons and this event was documented by 廉識.