Lethe (2003)

Blurb:
Mazda Hun is a soldier caught in a web of political and military struggles beyond his comprehension. Captured by the government, they sentence him to Lethe. Society doesn’t believe in the death penalty anymore. They’ve modernized the paradigm of punishment.

Lethe has many names: mercy, treatment, repair, reformation and rehabilitation. Some even call it justice. The Lethe procedure inflicts no pain and is over quickly, but its victims consider it a fate worse than death.

Lethe is the execution of a person’s soul. They make room for a new personality that will remember nothing of the old. Those who undergo the process don’t seem quite human ever again. And Mazda Hun’s time is running out fast.

Source: www.anisearch.com/manga/15037