4 years later
Tanjiro's POV
It's my fifth birthday and Oto-san said that I can start training tomorrow. Ani woke me up about an hour ago. After I got dressed we played for a while. Now we are making our way to the living room.
"Close your eyes." Ani said. "Ok Ani!" I said with a huge smile. I heard the living room door open. "No peeking." Ani said. I chuckled as a response. He grabbed my shoulders and guided me into the room.
"On the count of three, open your eyes. Ready?" Ani asked. I nodded eagerly. "One…two…three." Ani counted. I opened my eyes and gasped in excitement.
"HAPPY BIRTHDAY!" Everyone yelled. I started jumping in joy. "Thank you." I said.
Oto-san walked up to me. He picked me up and rested me on his hip. "Happy birthday Tanjiro." Oto-san said and kissed my forehead. Oto-san carried me over to the others as Ani followed.
"Happy birthday snowflake." Douma said. He messed with my hair as Oto-san put me down. "You grew up too fast." Daki said, as she trapped me in a tight hug. "It feels like just yesterday you were trying to eat Douma's hair while he was holding you." Nakime said. I slightly laughed but Douma pouted.
"That was yesterday." Douma pouted. All of us started laughing and Daki finally let me go. "Stop laughing!" Douma whined. "Akaza, make them stop." Douma said. He ran to Akaza and held his waist. We all stopped laughing because Akaza punched Douma's head off.
Koku kneeled down to eye level with me. "You ready to start training tomorrow?" Koku asked me. "YEAH!" I yelled in excitement. "What breathing style would you like to learn first?" Koku asked me. "MOON. I like watching you do it." I said with a huge smile.
Koku smiled at me. "You're so sweet." He said. "Less talking, more partying!" Daki said loudly. Hearing that exited me. "YAY!" I yelled.
"Tanjiro, wanna play pin the head on the demon hunter?" Ani asked. "What's that?" I asked. "We put a photo of a demon hunter on the wall, you have a picture of the head, we blindfold you, spin you around, and have you try to place the head on the neck." Ani explained.
I looked at him confused. "Yes?" Ani asked. " I thought we were supposed to kill demon hunters." I said.
"You can put the head on the hunter's sword like I do." Ani said. All the others started laughing. Even Nakime and Koku started laughing. "I am so proud of you two." Oto-san said. He came over to us and embraced us for about a minute.
"Prouder than Tanjiro's first words?" Gyutaro asked. "That was a good day for me as well." Koku said. "What happened?" I asked.
"I was talking to myself while watching you play. I mentioned the hashiras and you said kill. I looked at you confused. Curious about why you said that I said hashira again which you responded to by saying kill. I was over the moon with pride but still confused since I didn't teach you that word. I picked you up and went to the living room. I asked who taught you that. Turned out it was Kokushibou. So I gave him some of my blood." Oto-san explained.
"Can we play now?" I asked. "Yes we can. Who has the supplies?" Oto-san said.
The next day
Kokushibou's POV
I start training Tanjiro today. I have to say, he is extremely kind and sweet. I mean, he has stolen the hearts of all us uppermoons and has made master Muzan even softer than when he adopted Rui.
I'm not upset that I have the honor of training him. I actually volunteered to train him. I would see him watching me and others train. That's probably why he wants to learn moon breathing.
"HEY KOKU!" I heard Tanjiro yell. I turned around to see him running up to me. "Hey Tanjiro. Ready to begin?" I asked him, while giving him a pat in the head. "Yep." He said jumping a bit.
"Ok. Here." I said, handing him a wooden sword shaped like a Nichirin sword. He took it while examining it in bewilderment.
"This is shaped like the sword demon hunters use." I explained. "So, I'll be using one of those swords when I go undercover as one when I'm thirteen?" He asked. "That's correct." I said. "I can show you one and tell you more about these swords after training." I said. He looked up at me and nodded.
"You ready to start training?" I asked. "Mhmm." He said, nodding. "First, slash at that dummy." I said, pointing at the sparring dummy I pulled out for him.
He stepped up, took a breath, and attacked. I was gobsmacked. HE SLICED THE DUMMY IN HALF! My jaw is on the floor. I heard two gasps. I looked over to see both Akaza and Douma, looking at Tanjiro in shock.
"How did I do?" Tanjiro asked. I picked up my jaw to respond. "I have no words." I paused. "Was it bad?" Tanjiro asked. I kneeled down to look him in the eye. "Tanjiro, you cut a steel training dummy, in half, with a wooden sword, on your first try, when you've never held a sword before. You didn't do bad. You did amazing." I explained. Tanjiro's eyes widened and formed a huge smile.
Tanjiro looked away, so I looked as well to see what he was looking at, to see master Muzan walking over to us. "Hello you two. What's wrong with those two?" Master Muzan said, pointing at the still shocked Akaza and Douma.
"Hi Oto-san." Tanjiro said. "Hello Tanjiro… What happened to the steel dummy?" He asked. "I attacked it." Tanjiro said. Master looked shocked.
I stood up. "I told him to slash the dummy with the wooden sword I gave him. He sliced the dummy in half first try. That's also why those two are in shock." I explained.
"Tanjiro, that's amazing." Master said, picking Tanjiro up. "You excited to be a spy in eight years?" Master asked Tanjiro. Tanjiro nodded. "I'm gonna make Oto-san proud, but I don't like the sun. It hurts my eyes and burns." Tanjiro said.
"Haha. I will always be proud of you." Master said, then placed Tanjiro back down. "I'm gonna let you two get back to training." Master said. "Bye." Tanjiro said, waving bye to master, as master waved back at him.
When Master walked past the still shocked Akaza and Douma he grabbed both of them by their tops and dragged them.
"Ready to continue?" I asked Tanjiro. He looked up at me, smiling. "Yep." He said, chipperly.
A few hours later
"I think that's enough for tonight." I said, putting my sword back into it's sheath. Tanjiro looked up at me. "Ok. Can you tell me about the swords?" Tanjiro asked. "Ok. Go sit down and wait while I put all this away." I said. "Can I help?" He asked. "No, some of this could harm you. But you can put the wooden dummies that aren't broken away." I said. He smiled at me then ran off to put away the, still intact, wooden dummies.
He is such a sweet kid. I quickly ran around to clean up all the broken wood and steal. This kid is a natural, but, I'm gonna need a broom for all these tiny pieces.
He only has to put away the three wooden dummies we have left. I have to buy A LOT of steel training dummies. Nah, I'll just ask master Muzan if we can use some demons he doesn't like, to use for training. I might be able to convince him to let us use Douma next time.
I looked over at Tanjiro to see he was almost done putting the last one away. I walked over to the bench. Right as I sat down, I saw Tanjiro running up to the bench.
"Do you have the wooden sword I gave you?" I asked him. He ran to grab the sword that was on the floor, then ran back. He handed the sword to me, sat down, then turned his body to face me.
I took the sword and showed it to him. "The sword that demon hunters use are called nichirin blades or color changing swords. They are made out of the only metal that can kill demons, but only if the slice the neck, and cut off the head. Every demon hunter has their own. The color that it changes into depends on the slayer and breathing style. You will probably have a purple one." I explained.
"Why purple?" Tanjiro asked. "Moon breathing." I said simply.
"I have a question." Tanjiro said. "What is it?" I asked, curious about what he has a question about. "Someone asked me to ask you if you have a crush on Oto-san." He said.
I went red. "Do you even know what having a crush on someone means?" I asked him, trying to calm myself down. "Nope." He said. "Who asked you to ask that?" I asked him. He paused for a second before answering. "Douma." He said in a sing-songy voice.
I'm gonna kill him.
"You're not old enough for that. Why don't you either go rest or go play." I suggested. He smiled up at me. "Bye Koku." He said before running off.
Tanjiro's POV
I ran off to where Ani said to meet him after training. I went inside the room and saw Ani.
"Hi Ani." I said, making him notice me. "Hey Tanjiro. What happened after you asked him?" Ani asked. "He went red, asked me if I know what having a crush on someone meant, I said no, asked me who asked me to ask, I framed Douma, he said I wasn't old enough to know, then I left." I said.
"That means he does." Ani said, walking over to me. "Ani, why did you want me to ask and what does having a crush mean?" I asked.
"Because of how they act and I didn't want to get in trouble. A crush is when you like someone the way Douma and Akaza like each other when they think they're alone." Ani explained.
"You mean when you use your spiders to spy on them?" I asked Ani, confused. He smiled at me and placed his finger on his lips, making the shoosh symbol. "Remember, that's a secret." Ani said.
I smiled at him and mimicked his movements. We both started laughing.