Golden Kamuy is the gift that keeps on giving.
Volume 15 got many more revisions and added panels/pages than previous volumes, showing more about the stenka match with Gansoku (and his partners), and extra pages at the end of chapter 150 regarding Tsukishima and Tsurumi
Also, chapter 172 is available in HQ in JAPANESE
HERE
And a summary of the chapter on the spoiler below
! Kadokura informs Kirawus that part of his duties as a jailer at Abashiri involved arsehole probing.
New convict: Sekiya Waichirou
This guy likes to poison people, but instead of outright feeding them the poison, he lets them choose among poisoned and NON poisoned foods, leaving the matters to luck
! The convict leads Hijikata into taking one of the poisoned eggs, telling him otherwise he won´t tell him where is Ushiyama. (He did the same with Ushiyama, telling him he already got Hijikata)
Sekiya wants to collect the tattooed skins.
! Sekiya (disguised) offers fish to Kirawus, unaware of his real identity. But when Kirawus offers the (poisoned) fish to Kadokura, he (Kadokura) trips and ALL of the fish fall back into the water.
Kadokura comments on the critically bad luck he´s had since birth, and retells of tragedies of his past.
! Ushiyama frees himself from his entrapment.
The End.