Another manga about the conflict between life vs. death, and the role of ethics in science and medicine. Both are fairly hard sci-fi (especially Breathe Deeply- the medical jargon gets intense in some sections), and are full of drama
Susamu Nakoshi, a man disillusioned with life, meets Manabu Ito, a young medical student bored with life. To relieve his boredom Ito offers Nakoshi 700,000 yen to undergo a trepanning to see if it will unlock his sixth sense, and Nakoshi eventually agrees. However, much to his dismay and chagrin it actually succeeds, and now Nakoshi must contend with seeing homunculi, the metaphysical and symbolic representations of a person's psychological disorder. He now helps people, usually against his own will and often theirs as well, with resolving their psychological problems.
Both Himitsu and Homunculus are medical/psychological sci-fi manga about delving into people's minds. The former is a forensics manga about watching a dead person's memories, and the latter is about a man who can see people's inner selves. They also both have an element of mystery to them- Himitsu is a crime drama, and the main character in Homunculus is often preoccupied with figuring out why people look certain ways. Lots of great drama, though some readers may find bits of each disturbing.