1. How did Genya figure out his demonic powers?

2. Why does the demon slayer mark end one's life at 25 years specifically?

3. Why was Zenitsu given a sparrow instead of a crow?

4. How is it possible that the Muscle Mice can carry heavy nichirin katana?

5. Why did Genya want a color-changing katana in the Final Selection if he uses a gun and a short sword thing?

6. Why was Obanai not impressed by the death of the first Upper Moon in over a century and instead said it was "JUST Upper Moon Six"?

7. Is the "Hinokami Kagura" Sun Breathing itself?

8. How did Muzan figure out the whole demonizing thing?

9. How did Muzan find out his weakness to sunlight without being in the sunlight

10. What was the point of giving Tanjiro the ability to understand birds?

11. How come Zenitsu can't understand birds, but there are some scenes where he seems to understand Chuntaro?

12. If Doma is emotionless, why does he act like he has emotions?

13. How did Gyokko find the Swordsmith Village?

14. Why was Hantengu the only one brought along to the village when Doma wanted to go?

15. Does Kokushibo only stay in the Infinity Castle?

That's it. Idk how many are answerable, but I'd like to know if the answer doesn't exist.

1. Genya figured out his demonic powers when he ate demon flesh and survived, gaining enhanced abilities and senses.

2. The demon slayer mark ends one's life at 25 years specifically because it's the limit of how long a human can withstand the strain and burden of constantly fighting demons with their enhanced abilities.

3. Zenitsu was given a sparrow instead of a crow because he was not confident in himself and was not trusted to handle the responsibility of a crow.

4. The Muscle Mice are able to carry heavy nichirin katana because they are stronger and more durable than regular mice and have been trained for the task.

5. Genya wanted a color-changing katana in the Final Selection as a personal preference and for added visuals during battle.

6. Obanai was not impressed by the death of the first Upper Moon in over a century because he had a personal connection to the previous user of the position and did not see the current Upper Moon Six as a worthy replacement.

7. The "Hinokami Kagura" Sun Breathing is a specific technique within the overall Sun Breathing style.

8. Muzan figured out the whole demonizing thing through trial and error and experimentation with demon blood and flesh.

9. Muzan found out his weakness to sunlight through experimentation and observation of his own physical reactions and weaknesses.

10. Tanjiro's ability to understand birds serves as a symbol of his connection to nature and his overall empathy and understanding of all living beings.

11. It's possible that Zenitsu can understand birds, but it's not a focus of his character and is not specifically shown or mentioned in the story.

12. Doma may act like he has emotions as a means of manipulation and to better blend in with human society.

13. Gyokko found the Swordsmith Village through his ability to sense and manipulate sound waves, allowing him to locate and track down the village.

14. Hantengu was brought along to the village because he was the most skilled in deception and manipulation, which would be useful in infiltrating the village and gathering information.

15. Kokushibo primarily stays in the Infinity Castle, but can venture out when necessary or when he senses a powerful opponent.

1. Genya figured out his demonic powers when he consumed his first demon's flesh during the Final Selection. This awakened his demon abilities, specifically the ability to eat and digest other demons, gaining their powers and abilities in the process.

2. The demon slayer mark ends one's life at 25 years specifically because it is a side effect of using the Breath of the Sun technique. This technique greatly enhances a demon slayer's strength and speed but puts an immense strain on their body and shortens their lifespan.

3. Zenitsu was given a sparrow instead of a crow because sparrows are specifically trained to guide Thunder Breathing practitioners. Zenitsu is a Thunder Breathing user, so he was assigned a sparrow to assist him in locating demons and providing support during battles.

4. The Muscle Mice are capable of carrying heavy nichirin katana because they possess exceptional physical strength and agility. Their bodies are specifically adapted for carrying and maneuvering with heavy objects.

5. Genya wanted a color-changing katana in the Final Selection as a demonstration of his unique fighting style and abilities. While he primarily uses a gun and a short sword, having a color-changing katana would enhance his versatility and possibly catch his opponents off guard.

6. Obanai's lack of enthusiasm regarding the death of the first Upper Moon in over a century can be attributed to his pride and high expectations. As a skilled and powerful demon slayer, he may have expected an even stronger opponent or felt that Upper Moon Six was not a significant threat compared to the other upper moons.

7. "Hinokami Kagura" is a breathing technique utilized by Tanjiro and his family. While it is closely associated with Sun Breathing, "Hinokami Kagura" itself refers to the dance and not the breathing technique. Sun Breathing is a separate and unique breathing style.

8. Muzan discovered the process of demonization through experimentation and research. He injected himself with a sample of demon blood, which transformed him into the first demon. Over time, he refined and perfected the demonization process to create stronger and more powerful demons.

9. Muzan discovered his weakness to sunlight through trial and error. Being a centuries-old demon, he would have encountered situations where he accidentally exposed himself to sunlight and witnessed the detrimental effects it had on him. Through these experiences, he realized that sunlight could severely weaken or even kill him.

10. Tanjiro's ability to understand birds was a trait inherited from his deceased father. It allows him to communicate with birds and other animals, gaining information and assistance during his travels. This ability adds an extra layer of connection to nature and aids him in his journey as a demon slayer.

11. Zenitsu's inability to understand birds is likely a personal limitation or a lack of focus on developing that particular skill. While there may be scenes where he appears to understand Chuntaro, it could be attributed to his heightened senses and intuition as a Thunder Breathing user.

12. Doma's seemingly emotional behavior despite being emotionless can be attributed to his ability to mimic human emotions. He has mastered the art of deception and can convincingly emulate emotions in order to manipulate and deceive both humans and demons.

13. Gyokko found the Swordsmith Village through his exceptional sense of smell. Being able to track scents over vast distances, he followed the scent of the Demon Slayer Corps members and eventually arrived at the Swordsmith Village.

14. Hantengu was the only one brought along to the village because he possessed the ability to split into multiple personalities, each with unique powers and abilities. Doma likely believed that Hantengu alone would be enough to cause chaos and wreak havoc in the village.

15. Kokushibo primarily stays in the Infinity Castle; however, he can venture outside if necessary. The Infinity Castle serves as his base of operations and as a defense against potential threats, making it a convenient and strategic location for him to reside.