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.
Longevity was a Xianxia novel that started from the visualization of the sun. The author was a good white goose. The background of the story was set in the chaotic era of the Jiazi period, the end of the dynasty, the era of demons and demons, and the decline of the immortal path. The protagonist, Chen Yan, traveled to this era and became a young man in a mountain village who relied on his blind sister for survival. By visualizing the sun wheel, he could achieve white bones and flesh, immortality, and his cultivation speed was very fast. Chen Yan relied on this ability to leave the mountain village, pursue the Immortal Dao, and cultivate Daoist techniques. At the same time, he also followed his own principle of living an ignoble life. His identity became more and more special. From the Great Chen butcher to the wanted Saintess of the Immortal Sect, to the respected Celestial Venerable Chen, and finally to the Great Sun Immortal Lord who saved the Immortal World. Based on the information provided, I am unable to provide more details about this novel.
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.
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.