What did Kohei Horikoshi draw before My Hero Academia?
Two full series, both cancelled, and a one-shot that refused to die.
Horikoshi’s pre-2014 bibliography is short and completely documented. Three one-shots ran in Akamaru Jump: Tenko (2007), My Hero (2008), and Shinka Rhapsody (2008). Then came two serializations in Weekly Shonen Jump, and the magazine ended both of them.
Oumagadoki Zoo (2010–11) came first. Barrage, published in the magazine under the title Sensei no Bulge in 2012, came second, and its cancellation after two collected volumes left him, by his own account, depressed and without ideas. What he did next is the hinge of his career: he went back to the 2008 one-shot. Viz later published Barrage in English, so both of the cancelled series can be read; only one of them ever got a second life.
THE ONE-SHOTS
Akamaru Jump · 2007 to 2008Tenko (2007)
The debut one-shot, a story of war and a sword, published in Akamaru Jump in 2007.
My Hero (2008)
The prototype: a sickly office worker turned hero. Six years later it became the foundation of My Hero Academia. The germ of the series is all here.
Shinka Rhapsody (2008)
The third one-shot, his last short work before serialization: a deep-sea story, and the least revisited of the three.
THE CANCELLED SERIES
Weekly Shonen Jump · 2010 to 2012Oumagadoki Zoo (2010–11)
Serialization number one: a zoo of supernatural animals and the girl who would run it. Cancelled in the magazine; the idea of a cast of creature designs stayed with him.
Barrage (2012)
Serialization number two, as Sensei no Bulge: a space-opera war story with a slum boy standing in for a prince. Cancelled after two collected volumes; Viz published it in English in 2013.
What survived
From the zoo: the creature design. From Barrage: a character who would be rebuilt as Katsuki Bakugo, and asteroid-sized determination. From My Hero: everything else.