Kosu and the team were shocked to hear Ryota's suggestion that Dr. Kuro might hold the key to Jinpei's condition. They were well aware of the atrocities committed by Dr. Kuro and the Black Sun organization, and the thought of working with him was unsettling.

Kosu, Jinpei, and Sakura were stunned when they heard Ryota's suggestion that they should consult Dr. Kuro, the mad scientist of Black Sun, who had just caused chaos in their recent mission. They were well aware of the atrocities committed by Dr. Kuro and the Black Sun organization, and the thought of working with him was unsettling. Sakura's expression was fierce, and Kosu's hand twitched slightly on the hilt of his sword.

"Dr. Kuro? Are you kidding me? He's a criminal who experimented on innocent people!" Sakura exclaimed.

"I know it sounds crazy, but Dr. Kuro is the foremost expert in researching dungeon's hearts. If anyone knows what's going on with Jinpei's condition, it's him," Ryota explained calmly. 

Ryota also revealed "Dr. Kuro had made a deal with the authorities to give them all of his research data in exchange for being allowed to build a research room in the prison. You guys can take advantage of that." 

Jinpei hesitated for a moment before speaking up, "I know it's a risk, but if there's a chance that Dr. Kuro can help me, then I'm willing to take it. I don't want to endanger anyone, but I also don't want to live with this uncertainty."

Despite their reservations, Kosu and the team knew that they had to investigate every possible lead to help Jinpei.

Kosu nodded in agreement, "I'll go with you to ensure your safety. But we need to be cautious and not let our guard down."

Sakura reluctantly agreed, "Fine, but I'll be on high alert. If Dr. Kuro tries anything suspicious, I won't hesitate to intervene."

They decided to visit Dr. Kuro in the prison and see if he had any information that could be useful.

As they arrived at the prison, they were greeted by a stern-faced guard who led them to Dr. Kuro's research room. The room was filled with various magical instruments and research papers. Dr. Kuro was sitting at a desk, examining a glowing crystal.

Kosu and the team approached Dr. Kuro cautiously, not knowing what to expect. Dr. Kuro was waiting for them in his laboratory, surrounded by various apparatus and machines. He greeted them with a sly smile, "What a surprise, the heroes who foiled my plans have come to visit me. What can I do for you?"

Jinpei explained his condition, and Dr. Kuro listened attentively, nodding his head as he examined the data. He explained that Jinpei's high density level of magic particles was a rare condition known as "Dungeon Heart Resonance." It occurred when someone's magical wavelength matched that of a dungeon's heart, resulting in an excess of magical energy.

But this information Kosu and the team already know, what they want is a cure for this situation. "Tell me, do you have a cure?"

After a few moments of silence, he spoke up, "Yes, I've seen a similar case before. It's rare, but not unheard of. I can help you, but I require a favor in return."

Kosu narrowed his eyes, "What kind of favor?"

Dr. Kuro's smile widened, "A simple one. There's a dungeon that I've been interested in exploring, but it's too dangerous for me to go alone. I need a team to accompany me, and I think you're just the right people for the job."

Sakura crossed her arms, "Why should we help you? You're a criminal."

Dr. Kuro shrugged, "Think of it as a trade. I help Jinpei, and you help me. It's a win-win situation."

The group exchanged glances, unsure of what to do. They knew that Dr. Kuro was not to be trusted, but Jinpei's condition was also a matter of concern. They needed to make a decision, and fast.