Tanaka is
Japanese
Part of
Haiku form
Middle
stanza in
sonnets
A full Haiku sonnet is composed of three parts: a haiku (5-7-5), a tanaka (7-5-7), then another haiku (5-7-5). Of course, creating one in English is just silly, because whereas in Japanese the haikus resonante due to Japanese being a very melodic and rhythmic language, English is neither, and so it just sounds silly and causes a lot of people to think that Japanese poetry is just about getting the right syllable counts.