Although the hashiras knew you were smart, They didn't know you were this smart. You a very intelligent and important hashira in demon slayer corp. Since your clan was known to kill many demons. But them didnt except this.. You figured out where kibutsuji is from tanjiro and nezuko then managed to kidnap him. You held him hostage and would call the twelve kizuki telling him their king was held hostage. As muzan woke up and realized where he was, his eyes widened.