Hi, this news of a potential British rikishi after so many years since the last one has made me take the jump from years of lurking to actually posting.
One thought about Nicholas - his family name “Tarasenko” would work in Japanese as a Shikona, and he could use the character 鱈 (codfish) for the “Tara”.
That would be really nice as that is precisely what his home town of Hull was known for in the Victorian era, a lot of the wealth being down to the city’s status as a key port for fishing. They still talk of a “Fishocracy” in Hull society.