I don't own Digimon, but I love it deeply. Please, review my story.

Prologue

Izumi Masami and Izumi Yoshie had two sons. The older, Minori, had been born prematurely in the 29th day of December of 1989 and almost died. His health stayed fragile but he was able to overcome the misfortune and live happily. The younger son, Koushiro, wasn't born in that family. He had been adopted after his biological parents (who were related to Izumi Masami) passed away. Koushiro had been born in the 31th day of August of 1990. The two brothers loved each other very much despite being very different.

Minori had black curly hair and big brilliant brown eyes. He was always easily excited. He loved to watch anime and read manga about heroes and their adventures, usually pretending to be a hero himself. Minori couldn't practice sports or attend to gym classes because of his weak constitution, but tried his best to not let his frustration overtake him. If someone worried about the boy, he'd grin and say that he was totally fine. Koushiro, a red-haired kid with black eyes, was quieter and shy. He loved to learn new things; he had an infinite curiosity. Koushiro was the most sensible and responsible of the two brothers and tended to worry about Minori whenever he tried to put much pressure on his body. For example, when Minori was six years old he bet with other kids that he could run three times around a park nearby his home. Koushiro pleaded for his brother not to do that, but was unable to stop him. After completing one lap, Minori fell to the ground, feeling chest pain and difficulty in breathing. Koushiro, crying, ran to his side, asking if he was okay, while one of the older kids around called an adult. Minori forced a smile to his brother and said:

"Stop crying, you silly Koushiro. Don't you know that your Nii-chan is strong and invincible? I'm totally fine!"

Minori was taken to the hospital; fortunately his state wasn't too serious. When his parents arrived they firstly talked to the doctor and picked up Koushiro, who was being watched by Hinowa-san, a neighbor. After picking the crying little boy, they went to see the older one who had been medicated and was ready to go. The parents scolded him.

"Minori! How many times have we told you that you can't run? You have to be responsible! Don't you know that your health is fragile?" Yoshie was angry and concerned, trembling lightly as she spoke.

"Don't you understand, son? We just want what is the best for you. You can't push yourself too hard. Promise us that you won't do this again!" Masami spoke seriously.

"The other kids said that I couldn't do it! If I had chicken out, they would call me loser!" Minori protested. "Koushiro, I told you already to stop crying! I'm fine!"

"If you didn't want him to cry you shouldn't have been so reckless, Minori! You must stop putting your health in risk!" Yoshie scolded. She was almost crying too.

"Stop treating me as if I'm weak! I'm tough! I can do anything I want!" Minori replied, but it was pointless for him to protest. Minori had been forbidden to go outside to play for a week.

One night of that week, he was woken up by a sobbing coming from the bed next to him.

"Koushiro, why are you crying?"

"I-I'm not crying." The little boy hidden under the blanket replied. Minori had already stood up and forcefully took the blanket off of his little brother.

"I can see that you're crying. Why don't you tell me what happened?"

Koushiro hid his head under his pillow and didn't say anything. Minori was becoming worried.

"Is it because of what I did that day?" He asked sadly.

"It's n-nothing, really."

"I know that you're hiding something from me! Your incredible Nii-chan is a true lie detector, don't you know?"

After hearing that, Koushiro trembled.

"Y-you're not my brother."

"What… did you say?" Minori asked, astonished.

"I was thirsty… s-so I got up and… I heard Okaa-san and Otou-san saying that… I-I'm adopted." Koushiro managed to say. Minori paled. He took the pillow off of Koushiro's head and made him sit to face him.

"What kind of joke is that? It's not funny!"

However, the older brother knew that Koushiro didn't have the habit of joking. He didn't look like someone who was lying either. Also, he had referred to his parents in a surprising polite way.

"Koushiro, let's talk to Tou-chan and Kaa-chan! I'm sure they will tell you that you misunderstood-"

"It's not a misunderstanding! I don't want to talk to them about that!" Koushiro protested.

"Then what do you want to do? W-what are we going to do?" Minori was getting anxious. His little brother looked at him; his face was completely wet.

"Do you hate me?" He asked timidly.

"What? Of course not! I'm nervous, but I'm not angry at you or anything!"

"B-but… I'm not your brother…"

Minori slapped Koushiro, startling the red-haired.

"Stop saying nonsense! Of course we are brothers! We're still the same people we were yesterday, therefore we are brothers! I'll be always your Nii-chan!"

Koushiro stared at his brother for a moment and then he hugged him, tightly.

"T-thank you… I-I love you so much."

"I love you too." Minori said, hugging him back. "If you don't want to tell Tou-chan and Kaa-chan, you don't need to. We can keep it just to ourselves. Everything is going to be just fine. I'll be here for you."

Minori remembered Koushiro's crying face and realized that it was usually because of his irresponsible big brother that he cried. That was one of the rare occasions in which the smaller boy was crying over something else. The dark-haired boy felt useless; he didn't know what to do to make Koushiro feel better. Everything had become so complicated suddenly. The least he could do was to not hurt him anymore.

"Koushiro, I'll be a better Nii-chan for you. I won't scare you anymore or make you worry about me. So promise me that you'll never cry again, okay?"

"Okay." Koushiro whispered. Then, they heard a loud sound coming from the street. They ran to the balcony and saw two large monsters fighting. They didn't know how much their lives would change because of that event.