The question of who the strongest sword user in anime is subjective and can vary depending on personal opinions and interpretations. However, there are several notable and powerful sword users in the world of anime. Here are a few characters often regarded as exceptionally skilled or powerful swordsmen:

1. Kenshin Himura - Rurouni Kenshin: Kenshin is the protagonist of the anime and manga series Rurouni Kenshin. He is a former assassin turned wandering swordsman, renowned for his mastery of the Hiten Mitsurugi-ryū style.
2. Guts - Berserk: Guts, the main character of the Berserk series, is a mercenary wielding a massive sword called the Dragon Slayer. He possesses extraordinary strength and skills, making him a formidable sword user.
3. Zoro - One Piece: Roronoa Zoro is a member of the Straw Hat Pirates in the anime and manga series One Piece. He wields three swords simultaneously and is known for his incredible swordsmanship and dedication to becoming the world's greatest swordsman.
4. Ichigo Kurosaki - Bleach: Ichigo is the main character of the Bleach series, and while he primarily utilizes a unique sword-like weapon called a Zanpakuto, his sword fighting skills are formidable. He possesses immense spiritual power and can unleash powerful sword techniques.
5. Kirito - Sword Art Online: Kirito is the main protagonist of the Sword Art Online series. He is an adept swordsman within the virtual game worlds he explores, displaying exceptional speed, reflexes, and skill with various swords.
6. Samurai Champloo - Mugen and Jin: Mugen and Jin are two of the main characters in the anime series Samurai Champloo. They both possess distinct sword-fighting styles, with Mugen utilizing a wild and unorthodox approach and Jin employing a more traditional samurai style.

These are just a few examples of powerful sword users in anime, and there are many more notable characters with impressive sword skills across various anime series. The concept of strength can differ based on factors such as technique, power level, speed, and strategic abilities, so it ultimately comes down to personal preferences and interpretations.