Nishioka Kyodai consists of a brother and sister who were born in Tsu City, Mie Prefecture. First published in 1989, their works consist of both manga and ehon (絵本 / picture books and the like) and are often published by Seirinkogeisha (青林工藝舎).
Pictures of Nishioka Kyodai can be found here
Information garnered from here
Nishioka Bro-sis are a brother and sister team. Their first manga appeared in Morning in 1989. In 1991, they published their first work in Garo, and in 1997 became regular contributors to AX. One can think of their manga as children's stories on young adult themes of heartbreak, social obligation, suicide, and general existential crisis. Their work is reticent when not wordless, and has a floating flying groundless feeling, set within silent unmarked spaces, with waifish figures tousled and about to be blown away by the flow of life. Stylistically, their work derives from the abstraction, patterning, and attenuation found in early twentieth century illustrations to European fairy tales. Over the years, the line of Nishioka's drawings has become lighter and lighter, once thick brush strokes in the mid-90s, now at the brink of vanishing.