100-nen Ryuunen Shiteru Elf

Akitsu High School has stood for more than a century, and in all that time one particular student has never bothered showing up to class. The truth is that she is an elf from another world who has been held back in the same year for a full 100 years. When her classmate Ayumu finally tracks Elel down in her room, the ethereal beauty of legend is nowhere to be found, replaced by a spectacle so thoroughly pitiful he can hardly process it.