Webwhile not an outright confirmation that tanjiro made it past 25, it does heavily imply he survived long enough after his battle with muzan to grow old and father a. It is the struggle of humanity against demonhood, first to the internal conflict of tanjiro and then to the symbolic meaning of his transformation. Webthe hinokami kagura, or sun breathing is a technique in demon slayer passed on from yoriichi, all the way down the kamado family to tanjiro and his children. Webdemon slayer's manga ending reveals the ultimate fates of tanjiro and nezuko, although some reading between the lines is necessary to get it all.
