Aketa Katsuyuki is a retired Japanese civil servant, and member of the Kansai Ki-in. He has spent much of his retirement travelling around the world teaching Go. He is in South Africa at the moment. After spending 2 months teaching in Stellenbosch, he is now in Cape Town, where he will stay until the end of February. He will teach in Johannesburg during March and April, before returning to Japan.
Also known as Aketa-sensei, or just Sensei to many South African go players, Mr. Aketa met up with Chris Visser while teaching Go in Mongolia. He acted as an internet referee for Chris so that he could take part in the later stages of the South African Closed in 2004. Through his later contact with Chris, Mr. Aketa came to visit South Africa, and deciding that he liked what he saw, came back to teach for 5 months.
Here's a link to his entry in the European Go Database.