FA: Tokio Muroi, Dec 2001
2nd ascent: Toru Nakajima, Dec 2007
3rd ascent: Nalle Hukkataival, Apr 2009
4th ascent: Kensuke Hamada, Nov 2009
5th ascent Keita Kurakami, Nov 2009
On the same day, he also did Jigokuhen and Rampage, both 4dan./8A+/B, and both Tokio Muroi creations.
*I don't know if Bansousha is still considered 5.dan as this would make it ~8B+/C.
Photo: Tokio Muroi on Bansousha
Source: Hardcore express
It's in Japanese, so I owe big thanks to an anonymous friend who provided the information as a comment. Otherwise I'd never have found it.