[Well, when Yusei means "newly discovered," he means "almost 20 years ago," and at this point it's integrated into almost...everything. ha ha. So maybe Yusei's kinda giving the wrong impression here.]

The problem is if it ever turns in reverse...

[At this point, Yusei's face visibly crumples.]

When that happens, the energy it was giving out ends up rebounding. It can be...catastrophic.