Hyouge Mono deals with serious, sometimes tragic material, but with a slightly askew and subtly funny point of view. It's set in the Sengoku Period, though, so it's not modern and certainly not set in a high school.
You might give
Welcome to the NHK! a try. It's often quite hilarious, but the subject matter itself is quite serious. I wouldn't call it tragic, though it comes close in spots. The characters are young adults in their late teens and early twenties. There is a romance, but it's pretty unconventional.
Anime is rarely tragic by the usual dramaturgical definition. As a popular entertainment, it generally avoids difficult material and usually ends on a positive note.
Puella Magi Madoka Magica does have some classical tragic features (it's based loosely on Goethe's
Faust), but it's not very comedic. It's set in a middle school, and the main characters are all girls 13-15.