"I" (Boku) love math. Just after the high school entrance ceremony, "I" meet a beautiful girl: Milka. Milka is a mathematical genius. She gives me many math problems, she shows me many elegant solutions. Milka and I spend a long time by discussing math in the school library.
One year later, I meet another mathematical girl: Tetra. Tetra is one year younger than me, and asks me to teach her math. While I teach her, she begins to understand math and to love its elegance gradually.
In the first volume, we talk about Fibonacci Numbers, Harmonic Numbers, Finite and Infinite Sums, Factorization, The Bazel Problem, Partitions of the Integer, and Generating Functions.
In the second volume, we talk about Pythagoras Theorem, Elementary Number Theory, Group, Ring, Field, and Fermat's Last Theorem.
In the third volume, we talk about logic puzzles, Peano arithmetic, epsilon-delta, Cantor's diagonal argument, Hilbert's program and Gödel's Incompleteness Theorems.
Why don't you join us?

Kenn's Comment:

"Are we apart, even when our radius is 0?"
"Even when our radius is 0, a circle is a circle; a circle that begins at a single point.
 
Good lord. I won't lie. I hate math. I'm terrible at it. Formulas confuse me. Graphing formulas nearly killed me. Large equations hurt my head. I'm mathmatically retarded, so to speak. But this...this was something completely different. As much as I hate math, I couldn't help but fall in love with this series. The way that math so effortlessly is woven into the story almost makes the math understandable. It's got explanations and all, but most of it went clear over my head. If it was music theory/history or even chem or bio I'd be able to understand but alas, math is my kryptonite.

Anywho, the manga is based off a series of novels (go figure), and there are 3 series of the manga going, each by a different artist. Each series corresponds to 1 of the volumes of the novel. The author's site is here, and can be accessed in English. The novel is also available in English, for those who really want to wrack their brains with the formula of loooooove.