This powerful sword with Ichimae Boshi looks like Go Yoshihiro
Shinogi-zukuri, Ihori-mune, extended Chu-Kissaki.
Fine Itame with Ji-nie, Chikei, Jifu-Utsuri and Sumi-hada on Omote
Slight Notare with Gunome Ashi

Boshi is Ichimai 

Broad Soshu style Nakago has One Ana

There is a small carbon inclusion in the Moto that Mr. Yoshikawa noted as "fine."

Hirosuke Koji 1555 was the son of Yoshisuke.  Shimada is highy influenced with Soshu Den.  Katana are 2 shaku,  2 or 3 sun.  Deep Jitetsu of "no bottom".   Hamon are Nioi-deki.

The examples of Hirosuke are famous for the most imposing Sugata of the school, resembling SoshuDen Nambokucho Dambira. He is a true Shimada great. His works are considered superior to Sukemune.

Signed:
      "Shimada Hirosuke"

Sato Kanzan states that Hirosuke is next to Yoshisuke among the top three makers of the Shimada school.
Shirasaya with gold double Habaki. NTHK by Mr Yoshikawa Sr, personally.
The owner guarantees this sword to pass Shinsa.