"I'm tired somehow."
Hiyori unusually showed weakness.
Sora worried. "Are you feeling sick?"
"My body is fine. But my heart feels heavy."
Kaito asked curiously. "What does it mean for the heart to be tired?"
Leo began explaining. "Mental fatigue. A different phenomenon from physical fatigue."
"Different?" Kaito asked.
"Muscle fatigue is physical damage. But mental fatigue is depletion of cognitive and emotional resources."
Hiyori nodded. "That's exactly it. Nothing bad happened, but I'm just tired."
Sora thought. "What's the cause?"
Leo wrote in his notebook. "Cognitive load, emotional labor, decision fatigue, etc."
"Emotional labor?" Kaito asked.
Hiyori answered. "Suppressing true emotions and performing required emotions. I feel like I'm always doing that."
Sora noticed. "Hiyori, you're always listening to everyone and smiling."
"I thought that was my role," Hiyori said quietly. "But it's tiring."
Leo supplemented. "Emotional labor is invisible but surely consumes energy."
Kaito thought. "Then me too? When I suppress anger."
"Yes," Leo nodded. "Emotional regulation requires cognitive resources."
Sora asked. "What other causes are there?"
"Decision fatigue," Leo answered. "Making dozens, hundreds of small decisions a day. They accumulate into fatigue."
Hiyori understood. "That's why sometimes I can't decide anything."
"A symptom of decision fatigue," Leo acknowledged. "The brain's energy is depleted."
Kaito asked. "But sometimes I'm tired even when I've done nothing?"
"Mental fatigue doesn't correlate with activity level," Leo explained. "Rather, internal conflict and anxiety can be the cause."
Sora supplemented. "Continuous thinking is also tiring."
"Rumination," Leo said. "Repeatedly thinking about the same thing. That's also a cause of fatigue."
Hiyori suddenly realized. "I've been thinking about the same thing lately."
"What about?" Sora gently asked.
"My role. What I can do for everyone. But I can't find the answer."
Leo said, "That becomes cognitive load. You keep trying to solve a problem with no answer."
Kaito suggested. "Then stop thinking?"
Hiyori smiled wryly. "If I could do that, it'd be easy."
Sora understood. "Trying not to think makes you tired again."
"Yes," Leo nodded. "That's why the quality of rest becomes important."
"Quality of rest?" Kaito asked.
"Not just resting, but rest that allows cognitive and emotional recovery," Leo explained.
Hiyori asked. "Specifically?"
"It varies by person. But basically, reduce cognitive load. Reduce decisions, reduce emotional labor, stop rumination."
Sora suggested. "Create time when you don't have to think about anything?"
"A mindfulness approach," Leo acknowledged. "Just observe thoughts without getting caught up."
Kaito said, "When I'm gaming, I'm not thinking about anything."
"That's also one method," Leo nodded. "Entering flow state reduces fatigue."
Hiyori thought. "I haven't enjoyed anything lately."
Sora said gently. "Hiyori, you're always working hard for others."
"But that might be the cause of my fatigue," Hiyori realized.
Leo said, "Self-sacrifice works short-term. But long-term, it leads to burnout."
"Burnout..." Hiyori murmured.
"Burnout syndrome. An emotionally, physically, and mentally depleted state."
Sora worried. "Hiyori, please rest."
Hiyori smiled. "I might have forgotten how to rest."
Kaito said, "Let's make today a day of not thinking."
Leo suggested. "An experiment in cognitive rest. Don't decide anything, don't expect anything."
Hiyori let out a small breath. "That sounds really appealing."
Sora nodded. "Heart fatigue is proof of working hard. But resting is also important."
The four sat quietly. Acknowledging mental fatigue was the first step to recovery.