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.
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.
To design such a lesson, consider the interests of first graders. A story like 'Goldilocks and the Three Bears' could be great. You can begin the lesson by showing pictures related to the story to pique their curiosity. While telling the story, pause at key moments to ask for predictions. For instance, when Goldilocks enters the bears' house, ask the students what they think she will do next. After finishing the story, you can have the students act out parts of it. This not only reinforces their understanding of the story but also helps in their language development. First graders learn best when they are actively involved, and this kind of lesson plan with a story caters to that.
Yes, in some fanfictions, Tanjiro is depicted as the reincarnation of Yoriichi. This concept adds an interesting layer to the story as Yoriichi was an extremely powerful and legendary figure in the original lore. The idea allows for new storylines where Tanjiro might inherit some of Yoriichi's skills or have a deeper connection to the past events related to Yoriichi.
Tanjiro's fate in the manga is that he ultimately passed away. This event was a significant part of the story's development and had a profound impact on the other characters and the overall plot.