After a fierce battle against the demon Heisuke, Goku had fallen asleep inside Fumiko's house, a girl he met in the village.
When the day arrived, Goku woke up, rubbing his eyes and yawning. When he looked at his body, he noticed he still had some injuries, though they weren't severe.
"Good morning, Goku," said Fumiko, who woke up before him.
"Good morning, Fumiko," said Goku, standing up and grabbing his katana. "Today I'm gonna leave and continue my journey..."
"I see..." whispered Fumiko. "Thank you for last night, you saved us..."
"No problem. That's what a demon slayer does. I hope I'll see you again, Fumiko. Bye..."
Goku left the house and began walking outside the village.
"Goodbye, Goku... May your path be safe..." said Fumiko, ensuring he couldn't hear her.
__________
Goku started to search for a doctor to heal his few wounds. After several minutes of searching, he reached another village. Here, Goku found a hospital.
"I hope I'll find someone useful here..."
Goku knocked at the door twice, and a woman with violet eyes, a white haori with flowers on it, and black hair gathered in a tie opened it.
"Hello, demon slayer. What do you need?" she asked.
"Are you a doctor? If so, can you heal my wounds?"
"Yes, I am a doctor," said the woman, allowing him to enter. "Come inside, I will heal you."
When Goku entered, he saw another young boy with green hair, violet eyes, and a hateful grin.
"Who the hell are you?" he asked.
"A demon slayer," replied Goku.
"Why are you here?" Asked the guy.
"Quit bothering our guest, Yushiro," said the woman.
Yushiro stayed silent.
"So... what's your name?" Goku asked.
"My name is Tamayo," she replied. "He's Yushiro."
"Why does he smell like a demon?" demanded Goku.
"Because he is one. He's the only demon I managed to create in all of my life. What about you, slayer? What's your name?"
"My name is Goku. Just Goku. No surname, from what I know."
When Tamayo heard that name, her heart stopped for a second. Goku... Could it be that Goku? She one she raised for five hundred years?
"What... what did you say your name is?" she asked again.
"Goku..." Goku said again. In that moment, realizing Goku was really that Goku, Tamayo's eyes welled up with tears, and without hesitation, she hugged him tight, as if she had just found a lost child.
"Is it... is it really you... Goku...?"
"Uhm... Excuse me, Tamayo-san, but I don't get it... Why are you hugging me?"
"I'm so happy you came back to me..." she said again, apparently ignoring Goku, but still hugging him. Then, she broke the hug. "Now I'll explain to you... Please, sit down."
Goku sat down. Tamayo and Yushiro did the same.
"I knew you'd become a slayer... But I'd never thought you would come back to me..." said Tamayo.
"Can you explain better?" asked Goku.
"Sure..." said Tamayo, "Goku, you... are a hybrid. Half demon, half human."
Goku's eyes widened.
"W-what?" He said, in disbelief, "Half demon? Since when?"
"Since your birth," replied Tamayo. "Earlier, you said you don't have a surname. But you do. Your surname, Goku, is Tsugikuni."
"Tsugikuni? Isn't it the same surname as the legendary Yoriichi, the one who created Sun Breathing?"
"Exactly, Goku."
Tamayo took a deep breath.
"In fact, you are his son."
Goku's eyes widened once again, even larger this time.
"I... I am Yoriichi's son?" He repeated. "And half demon, too? Is this a joke?"
"Nope. Everything's true, Goku."
"But if this really is true... why do I find out only now?" Asked Goku.
"Because your true identity would have killed you. Five hundred years ago, I was under Muzan's control. Yoriichi, your father, fought him, nearly killed him, and freed me. That's why I can say his name. Neither I, Yushiro, nor you is related to him. One day, your father came to me and asked me to take care of you for centuries after his death. To ensure you'd live forever, he injected you with demon cells, which turned you into a hybrid. You remained a baby for 500 years because your body had to adapt and to process the demonic cells in your body."
"You're immune to sunlight and have an infinite lifespan, but you do not have regeneration or unlimited energy, unfortunately. I abandoned you only when I realized you were starting to grow up normally. So you're physically nineteen, but biologically five hundred and twenty-seven years old. Also, just like your father, you're born with a Demon Slayer Mark, but you can't use it yet. That's all."
When Tamayo finished the explanation, Goku was in disbelief. All that information... was a lot to take in.
"You know what? I may believe you, but my katana doesn't," said the boy, standing up. "Until I have proof I'm really Yoriichi's son, I won't believe this. But... I do believe in the hybrid and mark story..."
Goku got outside the house with his katana in hand.
If I'm really his son... Then I should be able to use Sun Breathing...
With a movement of his sword, Goku said:
"Sun Breathing: First Form -- Dance."
Unexpectedly, from Goku's katana emerged crimson flames.
"It's true... I'm really a Tsugikuni..." he realized.
"Do you believe now?" asked Tamayo, who reached him.
"I do now," said Goku. "So hybrid, Yoriichi's son, and Sun Breathing, huh? Cool."
__________
One month passed. One month where Goku trained under Tamayo's wing to learn Sun Breathing and improve Flame Breathing. He knew: now that he was aware of his true identity, he had to hide it.
During this month, Goku learned four out of the thirteen forms of the Sun Breathing. The first, the second, the fifth, and the eighth. As for the Flame Breathing, he could use five out of the six forms.
After this month, Goku was ready to continue his journey.
"So... you're leaving?" Asked Tamayo.
"Yes," replied Goku. "Thanks for taking care of me for five hundred years... Okasan."
Tamayo's eyes widened, and she hugged Goku.
"I love it when you call me 'okasan'..." she said.
"I know you're not my biological mother, but..." said Goku, hugging her back. "For me, it's like you are."
Now that I think about it, I wonder who my mother is...
"Okay, okay, enough hugging," said Yushiro, irritated. "Don't get too close to Tamayo-san, Tsugikuni..."
"Come on, don't be jealous, Yushiro," said Goku. Yushiro snorted.
"Try not to die, Tsugikuni. Tamayo-san would be sad."
"I won't," said Goku, "Well, time for me to go."
But then, before he could leave, Tamayo asked him one more question.
"Goku, how will you hide your identity?"
Goku stopped for a bit, then replied.
"I will walk under the alias of Goku Urokodaki, in honor of my master Sakonji. As for the Breathing Style, I'll keep Sun Breathing hidden and continue using Flame Breathing. That's how."
"I see... take care, my son..."
Goku nodded.
My life just changed completely. Now that I know who my biological father is, I'm ready to face everything.
Chapter 4 - End