My thanks to Kōsen Jūdō no kenkyū 高專柔道の研究 for this picture from an article (in Spanish, but translated below) regarding Yokoyama Sakujirō (横山作次郎).

This was when he was about 22, or 23 years old and would have been around the time that he fought a match against the Ryōi Shintō-ryū Jūjutsuka – Nakamura Hansuke (中村 半助) Both men fought for 55 minutes, but as neither could prevail the match was drawn. Nakamura was declared champion of East of Japan and Yokoyama champion of the West.

"Yokoyama Sakujirō (横山作次郎) 22 or 23 years old, the photo is dated probably 1886-87.
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Yokoyama arrived at the Kōdōkan in 1886 (Meiji 19), and quickly participated in challenges, against Totsuka-ha school for example.
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In October 1887 (Meiji 20), he fought one of the most powerful jujutsukas of the time, called Nakamura Hansuke, they fought 56 minutes. We can imagine that the struggle will surely occur more in newaza.
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Even though K ōd ōkan had a preference for standing fight, Kan ō knew that his students should be prepared to face the practical mindset jujutsukas that mostly dominated the soil struggle.
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We can say that Yokoyama was Jūdō's first newaza specialist, although of course there should be other unknown to the public."

The original article can be accessed via: https://www.instagram.com/kosenjudonokenkyu/