Why is Tanjiro’s sword black? Is there any proper explanation?

So I’ve been rewatching Demon Slayer and this one thing still feels kind of unexplained. When Tanjiro first gets his Nichirin sword, it turns black instantly. Even the swordsmith seems kind of surprised and says something like it’s rare and not much is known about it. But the anime never really tells us what black actually means or why it happens.

I’ve read that the color of the sword usually reflects the user’s breathing style or personality, like Rengoku’s flame sword being red. So if that’s the case, what does black mean for Tanjiro? Is it related to his Sun Breathing or something else entirely? Or is it just meant to be symbolic?

I’ve seen some fan theories online but I’m curious if there’s any official explanation in the manga or any confirmed info from the creator. Manga readers or lore nerds, can you shed some light on this? Or is it just one of those mysterious things that was never fully explored?

• This topic was modified 3 months, 3 weeks ago by Wan Xiaoling.