Sure, Tanjiro masters Sun Breathing in the manga. It's a turning point that showcases his determination and progress. It also ties into the broader story and his quest for justice.
The Hashiras would likely show concern. Some, like Shinobu, would immediately start looking into possible medical solutions. Giyuu might be more reserved in his worry but would still keep a close eye on Tanjiro. The other demon slayers would also be affected. They look up to Tanjiro, so his sickness would lower the morale of the group. They would try to support each other while waiting for Tanjiro to recover.
You need to understand the monsters' behavior. Know when they are most vulnerable and where they are likely to pass by. Then place the thunder traps in those strategic locations.
In fanfiction, Naruto using the Flying Thunder God gives him a strategic advantage. He can set up traps by marking certain areas and then teleporting his enemies into those trapped areas. Also, it allows him to support his allies more effectively. He can teleport to their side in an instant when they are in trouble, like when Sasuke is about to be overwhelmed by an enemy's attack.
There was this girl who always had her headphones on. One day, she sat by the window. She took a deep breath in, and the music in her headphones seemed to amplify. It was a beautiful melody. As she breathed out, she closed her eyes. In her mind, she was in a meadow, the music creating the scene. With each inhale, she felt more alive, and with each exhale, she drifted further into the story the music was telling.
Tanjiro might use his sense of smell to detect hidden threats. Since his sense of smell is super - enhanced, he could sniff out any demons or traps in the way of saving Rengoku. For example, if there are demons disguised as allies, Tanjiro would be able to tell by their scent.