Identity is an extremely fascinating subject matter for a horror manga.
However, much nuance and skillful character work is needed to handle it with effectiveness, whereas authour Higashino Keigo seems incapable to write even a single multifaceted character, instead proposing a cast of flat caricatures that do not go through any type of development whatsoever during the course of the story. The lack of character depth makes it even harder to stomach the plot: a few interesting ideas and pleasantly unsettling scenarios here and there, but overall a painfully childish spookfest with a complete lack of imaginative developments or interesting psychological explorations. The author refuses to go for a more subtle, quiet horror that would've better suited the premise's potential and instead opts for cheap distasteful scares that dont even pack a real punch either because they're insanely predictable or they're not set-up properly, all of it relying on a ridiculously exaggerated, cartoonishly binary view of good and evil that makes you cringe more than it makes you scared. Heads isn't even a good trashy read: as entertaining as watching bread getting stale.