More than a year ago...
Muku was still on the blue planet with his girls enjoying life. One random day, he was messing around with his class and its abilities.
This included his only mental attack. It was a move he rarely used since his opponents would usually be too strong or too weak for it to be applied. For that reason, he mostly doesn't bother himself with it.
However, on that day he was quite bored and thought that he might as well give it a look. It was then that he was surprised by what it actually was.
Instead of being somehow derived from his Telekinesis like he thought. It was actually derived from his soul! It seems he was just too weak to notice it then. Unlike that day when he was a R3 Evolver.
Anyway, after the discovery, his interest was piqued. And so, from that day he would try to probe it any way he could as he wanted to make it stronger. At the very least, he felt that there was something to it that he was missing.