Children of the Sea is written and illustrated by Daisuke Igarashi. It was serialized in Shogakukan's seinen magazine Monthly Ikki. Shogakukan has released five tankōbon volumes so far, between July 30, 2007 and July 30, 2012. The manga is licensed in North America by Viz Media, who serialized it online at SigIkki.com and released the first tankōbon volume on July 21, 2009 and the second on December 15, 2009.
Children of the Sea was nominated for the 2008 and 2009 Osamu Tezuka Cultural Prize. Daisuke Igarashi was awarded a Japan Cartoonist Awards excellence award for drawing Children of the Sea in 2009. Children of the Sea was the recipient of an Excellence Prize from the Japan Media Arts Awards at the 2009 Japan Media Arts Festival. About.com's Deb Aoki commends the manga for its "vibrant, detailed artwork that takes its inspiration from nature, real people and real places" but criticizes the manga for its slow plot which "picks up the pace after a few chapters". PopCultureShock's Sam Kusek comments on the interactions between the main characters, saying, " all share something in common, the fact that they are outsiders from the norm. Ruka is not your normal girl. As athletic as she is, her attitude and aggression towards her teammates leave her high and dry for the summer. Consistently throughout the book, people are badmouthing her as she passes them on the street. Umi and Sora are obviously outsiders due to their extreme circumstances, wearing large robes to cover a majority of their skin and having to constantly bathe in water. Sora especially has a frail constitution, spending most of the book in and out of a hospital. All three are young children, and that is shown throughout the book, but they also have a unique sense of maturity that sets them apart not only from other children but most adults." Anime News Network's Carlo Santos commends the manga for its "subtle, seamless storytelling and first-class artistry combine to form a fascinating tale of the sea" but criticizes it for "mundane events and superfluous scenes sometimes slow down the plot". ICv2's Steve Bennett commends the manga for "the art is rich with photorealistic details which help to give the fantasy a solid grounding in reality, and has strong, emotionally honest characters which should make this young adult fantasy appeal to both fans of epic fantasy and contemporary teen dramas." Coolstreak Comics' Leroy Douresseaux comments that he is reminded of the "1980s ecological sci-fi comic book, The Puma Blues" when reading the manga. He also commends on Igarashi's "earthy art, with its busy line work and crosshatching and unsophisticated figure drawing, grounds this series in reality, which makes the moments of enchantment all the more breathtaking." He also recommends the manga to those who liked Inio Asano's Solanin.
