Heavy Object

is a Japanese light novel series written by Kazuma Kamachi and illustrated by Ryō Nagi. ASCII Media Works have published fourteen volumes since 2009 under their Dengeki Bunko label. It has received three manga adaptations. A 24-episode anime television series adaptation by J.C.Staff aired from October 2, 2015 to March 25, 2016.

Plot
In the future, the development of massive war machines called "Objects" have rendered conventional warfare and even tactical nuclear weapons seemingly obsolete. As a consequence of this military upheaval, all of the nations of the world have fractured into four coalitions which constantly wage war on each other; the "Legitimate Kingdom", focused on tradition; the "Capitalist Enterprise", which values profit; the "Intelligence Union", focused on knowledge; and the "Faith Organization", which values religion above everything else. With the perception that only Objects can destroy Objects, modern warfare is reduced to duels between Objects, resulting in shorter, cleaner, and safer wars. However, this all changes when two regular soldiers from the Legitimate Kingdom, Qwenthur Barbotage and Havia Winchell, use their smarts and ingenuity to destroy the "Water Strider" Object of the Faith Organization all by themselves. Having proven that Objects created by man can also be destroyed by man, Qwenthur and Havia are thrown into a new world of harrowing adventures and dangerous suicide missions, while together with Qwenthur befriending and saving the Legitimate Kingdom's Elite Melinda Brantini, of the Object the "Baby Magnum".

Official

 * Anime Series Official Site (Japanese)

Other Sources

 * Wikipedia Article on Heavy Object