Is that... Sakura Wars? Columns is one thing for GBC but this Sega title as well?
Pocket Sakura (Tamagotchi but with Sakura Wars characters) was a success so I guess SEGA really wanted to follow up by making handheld version of Sakura Wars game but Game Gear was already dead.
So the only choice was to release this game on Neo Geo Pocket or Game Boy.
Luckily their choosing of Game Boy was right since this game was selling well enough it later even followed by a sequel Sakura Wars GB2.