Hokenshitsu No Tsumuri-San

Hokenshitsu No Tsumuri-San:

Katakura Tsumuri is the school nurse who runs the high school's infirmary... which is good, because she's the one who needs to make use of it the most. Tsumuri has a weak constitution, and constantly tires herself out or faints from doing her day-to-day job. It doesn't help that she's also a space cadet and lazy at heart, so when she's not asleep in the infirmary's bed, she's got it covered in snacks and games. Her younger brother, Kouta, is a student at the school and spends plenty of his free time assisting his sister and unwillingly rescuing her from the demands of adulthood.