Tubame Syndrome

Another entry in the long list in the Harem genre. The story follows Taiga, an ordinary high school student, and his sister Tubame. Taiga cannot remember anything up to a few years ago and relies on Tubame to take care of him after an accident that he cannot remember killed their parents.

Can be read here

This anime provides examples of:
 * Accidental Pervert
 * Beware the Nice Ones: Taiga when very pissed off. he becomes part phantom and gets more pissed off.
 * Clothing Damage: Often.
 * Darker and Edgier
 * Eldritch Abomination: The Phantoms.
 * Fan Service: Unwanted Harem. Need I say more?
 * Furo Scene
 * Marshmallow Hell
 * Spell My Name With an "S": Tubame/Tsubame
 * Unwanted Harem