Rizu Ogata

Rizu is a short but well-endowed girl who wears glasses. Rizu has light brown hair and blue eyes.

She is a genius with math and science but terrible with liberal arts.

Rizu although she is seen to always have a poker face on, she's capable of showing emotions whenever she's happy or down. A math and science genius since young, she is known as the "Clockwork Thumbelina".

[Spoiler] She is very short at 143 cm (4 feet 8 inches), yet has the biggest bust size among the female protagonists at F cup, and possibly G when she measured it again in chapter 44. She becomes an H cup by the time she reaches freshman year at college. [/Spoiler]

[Spoiler] In "Thumbelina Supercomputer" route, She and Nariyuki Yuiga are dating. [/Spoiler]

(Source: We Never Learn Wiki)