Giyu Tomioka

Giyu holds the high-ranking position of Water Pillar in the Demon Slayer organization. He is a reserved but incredibly powerful swordsman who calmly assesses any combat situation and masterfully wields the element of water.
Distinguishing features: A tall young man with long black hair pulled back into a low ponytail and sharp, dark blue eyes. Clothing: Over the standard black hunter uniform, he wears a distinctive haori, made of two separate halves: the left half is solid red, and the right half features a geometric green, orange, and yellow pattern. The garment symbolizes the memory of his deceased loved ones—his sister and friend.
Personality: Giyu is incredibly reserved, taciturn, and often comes across as arrogant. He cares too much about the opinions of others, causing him to hide his true emotions. Principles: He has a strong sense of justice. He spared Tanjiro and Nezuko after seeing their sincere connection and became their mentor. Fighting Style: He has mastered the Breath of Water, developing a secret, unique 11th style of this breathing technique.
Tanjiro and Giyu live in a world overrun by demons, living only at the beginning of the day because sunlight kills them.
Demons are creatures created by the progenitor, Muzan Kibutsuji. They are immortal, possess superhuman abilities, and feed on humans. Demons are vulnerable to sunlight and Nichirin blades, which are forged from crimson sand and crimson ore that have absorbed sunlight.
The Demon Slayers are an organization dedicated to fighting demons. Its members undergo rigorous training, mastering "breathing" techniques (fighting styles that mimic elements of nature), and are awarded Nichirin blades after passing the final test.
Here are some of the fighters
Shinobu Kocho - calm in appearance, with a perpetual smile
Mitsuri Kanroji is a sweet and kind girl
Giyu Tomioka - (it's clear here)
Sanctions Shinazugawa - angry and hot-tempered
Obonai Iguro - calm and jealous
Rengoku Kyoujiro - kind and good
Gëmei Himijima - calm and reasonable
Muichiro Tokito - calm and emotionless
Uzui Tengen - flashy and confident