Back in time to when Jinbei left the hospital without telling anyone. Kosu searched everywhere for him but couldn't find him. With Sakura and Ryota still in the ICU, Kosu had no choice but to seek help from the Adventurer's Guild.

He met with the guild master, a wise and experienced adventurer named Tetsuo. 

The guild master called Kosu into his office and closed the door behind them. After a few moments of silence, the guild master spoke up, "Kosu, before we start talking about your affair, there's something I need to tell you. I am your biological father."

Kosu's eyes widened in shock. "What? How is that possible? My father lived with my mother and me from the time I was born until he died of cancer a few years ago."

Kosu sat across from the Guild Master, still reeling from the revelation that the man he had grown up calling "father" was actually his stepfather.

"I know this is a lot to take in, Kosu," the Guild Master said, placing a hand on Kosu's shoulder. "But I wanted to tell you the truth. Your mother and I had an affair while she was still with your biological father. It was a complicated situation, but he knew about it and accepted it because he couldn't give your mother the child she desperately wanted."

Kosu stared at the Guild Master, feeling a mix of shock, confusion, and anger. "So you're telling me that my whole life has been a lie?" he asked.

"I wouldn't say that," the Guild Master replied. "Your stepfather loved you as if you were his own son. He was a good man, and he knew that the most important thing was that you had a happy and healthy life."

"But why didn't you tell me sooner?" Kosu demanded.

"Your mother made me promise not to say anything," the Guild Master explained. "She wanted to protect you from the truth. But after what happened with Sakura and Ryota, I felt like you deserved to know. And I hope that you can forgive me for keeping it a secret for so long."

Kosu sat there for a moment, trying to process everything. It was a lot to take in, and he wasn't sure how he felt about it. 

"So, let's say you really are my father. Why do you reveal that now?" Kosu talk to the Guild Master, his voice fill with uncertain.

"Blood heritage", the Guild Master replied, his eyes fixed on Kosu. "It's a power that has been passed down through our family for generations," he explained. "It's a power that can be used for great good, or for great evil."

Kosu looked at him skeptically. "And what makes you think I'm capable of handling such power?"

The Guild Master replied. "I can see it in you, Kosu. It has awakened inside you. With the right training, you could become one of the most powerful adventurers in the guild."

Kosu frowned. "I don't know if I'm ready for that kind of responsibility."

The Guild Master nodded. "I understand it's a lot to take in. But I promise you, I will be with you every step of the way. I will train you, guide you, and make sure you use your power for the greater good."

Kosu felt a shiver run down his spine. He had never been interested in having any kind of special power, and the thought of inheriting something that could potentially be dangerous made him uneasy. "I don't know if I want this power," he said slowly.

The Guild Master nodded understandingly. "I understand your apprehension, but you need to know that this power will be yours whether you want it or not. It's in your blood. The only thing you can control is how you use it."

Kosu hesitated for a moment before nodding. "Okay," he said, steeling himself for what was to come. "I'll do it."

The Guild Master smiled, a rare sight for the stern Guild Master. "Good. I'll train you myself. It won't be easy, but I have faith in you."

Kosu felt a glimmer of hope. Perhaps this was what he needed to distract from Jinpei's sudden departure and the guilt of not being able to protect his friends. Maybe this power can help him make a difference in the world.