Ha's first published comics work was in
Green Lantern vol. 3 #36 (Feb. 1993), whose story, "The Ghost of Christmas Light", was written by
Gerard Jones. He would draw a number of comics for DC and
Malibu Comics, and did work for Marvel as well, illustrating the 1994 miniseries
The Adventures of Cyclops and Phoenix, which documented the childhood of the character
Cable. He would draw that miniseries' sequel as well, ''Askani'son''. Ha was one of the artists on the
Shade limited series which spun off from the
Starman series. He would subsequently illustrate a number of different properties for various publishers, including
Aliens: Havoc,
Superman,
JLA Annual, which included interiors and cover work. In 1999, he began illustrating
Top Ten, one of the series of Alan Moore's
America's Best Comics imprint for
Wildstorm. He would draw that series' twelve issues which ran until late 2001. Moore and Ha collaborated on the
Top 10: The Forty-Niners graphic novel prequel published in 2005. In 2002 Ha wrote "The Stronghold", an
Iron Fist story published in
Marvel Knights Double Shot #4, which represented his first published comics writing. In a December 2013 interview, Ha announced a sabbatical from
work for hire comics and expressed his desire to focus on creator-owned projects. In June 2015,
Dark Horse Comics selected for publication Ha's creator-owned series
Mae, which Ha funded through the
crowdfunding website
Kickstarter. The
Mae fundraising campaign, which was for a 68-page
Mae graphic novel written and illustrated by Ha, launched on April 24, reaching its $22,000 goal in 36 hours, and concluding with a total of $75,643. The book, however, will be published as an ongoing series rather than as a graphic novel. A
portal fiction story, it depicts sisters Abbie and Mae, recently reunited following Abbie's disappearance eight years earlier into a fantasy world of monsters, who have followed her back to her world in pursuit of her. The series holds a 7.8 out of 10 rating at the review aggregator website Comic Book Round Up, based on 35 reviews. In April 2022, Ha illustrated the second issue of
Wonder Woman Historia: The Amazons. Written by
Kelly Sue DeConnick, the three-issue limited series takes place before the birth of
Diana and tells of the creation of the
Amazons and how
Hippolyta became their queen. The first
Wonder Woman Historia: the Amazons issue was illustrated by
Phil Jimenez and the third by
Nicola Scott; an omnibus edition of the comics miniseries was released in June 2023. ==Techniques and materials==