ZenNezu

"I will protect you, Nezuko-chan."

- Zenitsu to Nezuko before falling asleep.

ZenNezu is the het ship between Zenitsu Agatsuma and Nezuko Kamado from the Demon Slayer fandom.

Canon
Before seeing her but knowing already that she was a demon, Zenitsu protected Nezuko from Inosuke because Tanjiro said that she was important to him.

When Zenitsu sees her for the first time and discovers that she's a cute girl, he quickly gets mad at Tanjiro because he thinks that Nezuko is actually his girlfriend instead of his sister. Later, when the misunderstanding is clarified, it is shown that Zenitsu quickly fell in love with Nezuko and tries to catch her attention by running after her or giving her flowers. He's shown to be deeply fond of her even on a short period of time, since on the Natagumo Mountain he refers to Nezuko as "the person he wants to protect" and she's his main motivation to run into the forest, claiming that Tanjiro is a moron for bringing a girl into the danger.

While he fights with his kasugaigarasu Ukogi (Chuntaro) he mentions that Nezuko is cuter than her. In the manga, on the Butterfly Estate, Zenitsu is shown talking with Nezuko when she's inside her box and showing her Shinobu Kocho's goldfish.

In the second chapter of the first Demon Slayer light novel, Flower of Happiness, Zenitsu asked Shinobu’s and Tanjiro's permission to take Nezuko to the flower field as he promised. There he saw a yellow flower and got sad thinking about his past, but Nezuko brought him back to present and cheered him up.

In the anime, Zenitsu asks Tanjiro if Nezuko would not be safer at the Demon Slayer Corps headquarters than travelling with them.

In the Mugen Train Incident, Zenitsu had a dream about Nezuko. He was holding her hand to show her a place where peaches were delicious and he said that he would make a flower crown with white clovers for her. There was a river on the way and when Nezuko got worried about that because she can't swim he offered to carry her and jump so she wouldn't get wet. She agreed as shown in the manga extras (Zenitsu's leap of joy).

When Nezuko got in danger fighting against the train demon, Zenitsu jumped to rescue her in his sleep, claiming he would protect her. Then they fought side by side against the demon. After the train derailed, Zenitsu protected Nezuko and other passengers, hugging them. When the sun rose, he helped Nezuko to go back to her box and carried her safely.

When Nezuko conquered the sun and was able to speak again, she welcomed him back to Butterfly state after a mission, blushing a bit. Zenitsu was overjoyed to hear her speaking, screaming loudly in excitement, saying she was amazing and asked her to marry him, saying he would feed her eel and sushi every day.

In the second chapter of the second Demon Slayer light novel, One-Winged Butterfly, during the pillars training, Zenitsu tells his fellow demon slayers that he has a girl he loves, Nezuko, who is waiting for him at Butterfly state. He said she would welcome him back, they would get married, he would feed her sushi every day and buy her a bunch of beautiful kimonos and they would live a happy and blissful life.

After the battle against Muzan, Zenitsu asked the Kakushi that if he died, they told his wife Nezuko that he loved her and he was brave and was thinking about her until the very end.

When Tanjiro became a demon and Nezuko tried to stop his attacks, getting injured in the process, Zenitsu screamed in agony, begging Nezuko to stay back and Tanjiro to stop. After Tanjiro became human again, Zenitsu told him he would spend the rest of his life making him atone for what he had done to him and his wife, referring to Nezuko. She looked at him flustered, wondering what he meant.

After these events, Zenitsu and Nezuko went to live in the Kamado house with Tanjiro and Inosuke. They would eventually marry and start a family, having two great-grandchildren by the names of Toko Agatsuma and Yoshiteru Agatsuma between them.

Differences between anime and manga
There are some differences between the anime and manga that may affect people’s opinion about the ship, particularly regarding Zenitsu’s ways.

Wisteria house: In the manga, Zenitsu just nods and bows down to Nezuko. In the anime, Zenitsu chases her across the room.

Butterfly state: In the manga, Zenitsu talks to Nezuko while she is in the box and he shows her Shinobu’s goldfish. In the anime, Zenitsu asks a Kakushi girl to go for a walk with him. In that part of the manga, he just said he would go outside and play. Kimetsu Academy: In the manga, Zenitsu says that Nezuko is so cute chewing her bread and that she looks like the protagonist of a Shoujo manga because she is so beautiful. In the anime, Zenitsu drools over Nezuko, Makomo and Shinobu.

Fanon
This ship is one of the most well-known inside the fandom because of Zenitsu's clear attraction toward Nezuko. A lot of people ships them and wants Nezuko to reciprocate his feelings once she becomes a human again. However, on the other hand, some fans dislike it because of Zenitsu's tendency to like a woman based solely on appearance or the fact she's a girl.

In the fandom, they are portrayed a similar way as in the canon-verse. Usually with Nezuko finally returning Zenitsu's affections. Zenitsu is also notably more gentlemanly and has a more mature attitude towards her, leaving behind his playboyish ways (liking every woman he sees) and ultimately decides to settle with Nezuko.

Fandom
FAN ART
 * ぜんねず tag on Twitter
 * ぜんねず tag on Instagram
 * ぜんねず tag on Pixiv

FAN FICTION
 * Zenitsu/Nezuko tag on FanFiction.net
 * Zenitsu/Nezuko tag on FanFiction.net

TUMBLR

Trivia
Zenitsu's voice actors both in Japanese (Shimono Hiro) and English (Aleks Le) seem to support the ship. Shimono Hiro usually screams Nezuko's name at many events and in Kimetsu Radio he mentioned Zenitsu is loyal to Nezuko and that he would use Thunderclap and flash against the pillars for wanting to kill her. Aleks Le made a drawing of Nezuko thinking about Zenitsu in one of his YouTube videos.