Iron Soul!! ZOIDS Hand-to-Hand Fighting

It's about a boy named Tekkon. Tekkon at first just loves baseball and has no interest in Zoids, calling them kid's toys. However, this changes after he meets a man called Commander O, and Tekkon quickly finds himself deep in the world of building models and participating in various competitions. He makes various friends along the way.

Though the kanji 鉄魂 is normally pronounced てつこん "Tetsu Kon", which translates to "Iron Soul", for this story it's written with a small "tsu" to make てっこん "Tekkon", the main character's name.