Kamitsuumi

The Tongans from the 70s.

This is probably the closest, being just one win off: http://sumodb.sumogames.de/Results.aspx?b=196303&d=15

https://www.sumo.or.jp/Jungyo/schedule_2022/ Aug 5: Tachikawa, Tokyo Aug 6: Funabashi, Chiba Aug 7: Saitama, Saitama Aug 11: Koga, Ibaraki Aug 14: Kasukabe, Saitama

There is a very similar table in the Japanese Wikipedia: https://ja.wikipedia.org/wiki/年寄名跡#襲名権を持つ現役力士

There was a pair of kanban ozeki in th Edo era: Shakagatake and Inazuma

I was wondering if you could extend this to actually quantify the rikishi classes, like the Hana no Nippachi-gumi, which are rikishi born in Showa 28 (1953), as compared to other birth years.

224kg at one point according to Nikkan Sports https://www.nikkansports.com/battle/sumo/news/201912120000316.html

Already reported on.

Nishonoseki (ex-Kisenosato) reported by Sponichi to be recently married, to a woman 6 years younger, whom he met after his retirement.

Hakuho giveth and Hakuho taketh away: https://sumodb.sumogames.de/Banzuke.aspx?b=200905 https://sumodb.sumogames.de/Banzuke.aspx?b=201207 https://sumodb.sumogames.de/Banzuke.aspx?b=202107

He's just outside your time range, but the tallest rikishi in modern times is Fudōiwa, who competed from 1940 to 1954 and was 214cm tall. Ōuchiyama, who retired in 1959 (barely makes it into the 6-basho era), was over 2m as well.

In terms of amount of time as a stablemaster (as opposed to just oyakata), no one could beat Chiyonoyama, who split off after Hatsu 1967, and his uchi-deshi ozeki Kitanofuji won the yusho the basho after.

Surely it's Ikenobou.

Another throwback:

Exactly like Hakuhō