Hyperbolic Time Chamber.
There was no sky, no ground, only endless pure white.
Light came from every direction, with no shadows and no points of reference, making it impossible to tell up from down or left from right.
Ten times gravity pressed down on every inch of bone like an invisible giant hand.
After training for a while without fully adapting to the tenfold gravity, Trunks dropped to his knees on the white ground, gasping for breath.
His light-purple short hair was stuck to his forehead with sweat, and his black combat jacket felt as heavy as iron under the gravity.
"This is—the Hyperbolic Time Chamber—" He struggled to raise his head and looked at Son Goku standing ahead of him. "One day outside—one year in here—"
"Yeah." Son Goku stood some distance away. He had not transformed into any other form and was merely standing there in his base form. "There's plenty of time here. Enough for us to—train slowly."
Trunks gritted his teeth and forced himself to stand. "Master, where do we begin?"
Son Goku tilted his head, seemingly deep in thought.
Then he raised a finger and lightly tapped his temple. "We start here.
"The brain?"
"No! The heart!"
He walked over to Trunks and asked, "Trunks, when you transform into a Super Saiyan—what does it feel like?"
Trunks froze for a moment, then recalled the sensation. "It feels like—my power is boiling. My blood is burning. Anger—endless anger—"
Son Goku nodded. "Right! That's the problem."
"Super Saiyan—is a transformation born of 'anger.' Anger lets you break through your limits, but it also makes you—unable to last. Like a fire: the hotter it burns, the faster it goes out."
He paused, his voice lowering. "What I'm going to teach you—is not how to make that fire burn