Deathnote

Deathnote (12 volume manga series)

Tsugumi Ohba/Takeshi Obata (2003)

I'm not a big violence fan, even in my comics; this does have a lot of frequent and indiscriminate murder, although mostly "off screen" and not graphic at all.  For older students it does raise questions regarding capital punishment, the battle of right vs. wrong, corrupt power, etc.  It's well done with twists and puzzles, interesting characters, and bits of humor.  The later issues tend towards inner monologues and less action.