Raku III Donyu (1599-1656)
楽三代 道入

Born as the eldest son of Jokei. He is also known as Nonko, later considered the most skillful Raku potter. He introduced the decorativeness into the Chojiro's stylistic tradition of monochrome black that eliminated decoration. In contrast to the massive presence of Chojiro's tea bowls, the individualistic expression has been reduced to a minimum.

References:
Signature and seal of Donyu, see: Encyclopaedia of Signatures and Seals (落款花押大辞典 Rakkan Kao Daijiten), Kyoto 1982, p. 1431ff