One of the hardest slab problems in the world. The impeccably smooth Fukano Slab ("impossible slab") was one of the last great problems in Ogawayama bouldering, initially solved by Toshimichi Kusano's Zutsu (8B), which starts centrally and traverses off left.
After many seasons of effort, climbing ground up and without a pad, Tokio Muroi filled the remaining lines on the slab Bansosha (8B) and Fuminsho (8B), before turning his attention to completing the obvious straight-up finish to Zutsu. He eventually succeeded in the wintery depths of December 2007, creating Kakusei – an achievement that went largely unnoticed outside Japan.
The problem came to wider attention in 2023 when other problems made claims to be the world's hardest slab and Yuki Miyashita's 2021 video of his extraordinary efforts to repeat the climb was discovered.
The line was subject of some controversy in Japan c.2020 after repeats were claimed where the climber drifted onto slightly easier ground to the left. It was later clarified by first ascensionist Tokio Muroi that a sloper on Zutsu was out. It’s not known if all the repeats before the clarification followed the strict line. [1]
6 successful ascents recorded.
| Climber | Style | Ascent Date | Suggested Grade | |
|---|---|---|---|---|
| Tokio Muroi | Boulder | worked | Dec 2007 | ||
| First ascent. | ||||
|
With no pads. |
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| Keita Kurakami | Boulder | worked | 24th Dec 2016 | ||
| Second ascent. | ||||
|
With one very thin mat to keep feet clean. References |
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| Mito Shimokawa | Boulder | worked | 18th Jan 2018 | ||
| Third ascent. | ||||
References |
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| Shinya Ando | Boulder | worked | 19th Jan 2018 | ||
| Fourth ascent. | ||||
References |
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| Junta Sekiguchi | Boulder | worked | 2020 | ||
| Yuki Miyashita | Boulder | worked | 2021 | ||
References |
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