what letter did zenitsu get

It's hard to say exactly. The contents of Zenitsu's letter could vary depending on the context and plot of the manga at that point.

Definitely not. The story doesn't depict Zenitsu and Nezuko as a couple. Their paths in the manga are more about their individual quests and battles against evil.

No, they don't. There's no such plotline in the manga.

No, Zenitsu doesn't die in the manga. He survives through the various story arcs.

Definitely not. In the manga, there's no such plotline of Zenitsu and Nezuko getting married. Their relationship is more focused on being comrades in the fight against demons rather than a romantic one leading to marriage.

I recommend the book "Omnipotent Agent". After the male protagonist retired, he became a male clerk in a lingerie store. However, he was later recruited by a beautiful woman into an organization and became a bodyguard to protect a beautiful school belle. He was the world's top assassin king and one of the top bodyguards in the protection world. He only protected her for five hours a day. I hope you like my recommendation. Muah ~

In Season 3, episode 15, the FBI got some important information from Neal's letter to Kate. In the letter, Neal mentioned that he had a secret lab that stored evidence of his cooperation with other criminals. This information caught the attention of the FBI, and they began to investigate Neal's relationship with the entire criminal organization. During the investigation, the FBI found some clues related to Neal's previous behavior. They found out that Neal had tried to reveal the location of his lab to Kate, but Kate had refused. As the investigation deepened, the FBI decided to take action because they believed that Neal's lab might be involved in illegal activities. In the end, they successfully brought Neal and the entire criminal organization to justice.

One common theme is self - discovery. Since Zenitsu has a complex personality, many fanfics focus on him finding out more about himself, his powers, and his place in the world. Another theme is friendship. He often forms strong bonds with other characters in fanfics, like Tanjiro and Inosuke.

No, Zenitsu doesn't die in the manga.

No, Zenitsu doesn't die in the manga. His character survives through the story.