Passage: A 24-episode anime adaptation produced by Gonzo and directed by Yusuke Yamamoto aired in Japan between July 9 and December 17, 2006 on Chiba TV and on later dates on other JAITS stations. Hiroshima Home Television, a local ANN station in Hiroshima, aired the series from July 16 to December 23, 2006. The series was coordinated by Satoru Nishizono, featured character design by Takahiko Yoshida, and the music was headed by Masao Fukuda. ADV Films licensed the anime for $240,000 and released the first DVD of the English edition in October 2007. In 2008 the English license was transferred to Funimation. Siren Visual has licensed the series for release in Australia and New Zealand.The anime has four pieces of theme music; two opening themes and two ending themes. The first opening theme, "Puzzle" (パズル, Pazuru) was written by Rieko Ito, composed by Kitagawa Katsutoshi, and performed by Round Table featuring Nino. The second opening theme is a remix of the first entitled "Puzzle (extra hot mix)" (パズル－extra hot mix－) which was produced by the same people as with the first opening theme. The first ending theme used for episodes one through twelve, "Odoru Akachan Ningen" (踊る赤ちゃん人間, lit. "Dancing Baby Humans"), was written by Kenji Otsuki, composed by Fumihiko Kitsutaka, and featured vocals by Otsuki and Kitsutaka. The second ending theme used for episodes thirteen through twenty-four, "Modokashii Sekai no Ue de" (もどかしい世界の上で, lit. "On Top of a Frustrating World"), was written and composed by Yugo Sasakura, arranged by Masanori Shimada, and performed by Yui Makino.

Question: Who were the vocalists in Dancing Baby Humans?
Otsuki and Kitsutaka