Dog Collar is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Handong highschool looks normal on the outside but turns into a gambling battleground. Student Duel Committee created by young masters of chaebol (rich) families held a secret martial arts competition ‘Dog Fight Club’. The reason being money. Cho Sang-Baek entered Handong Highschool after pursuing revenge and got the nickname Psycho after crushing all the bullies and getting everyone’s attention. Situations where the opponent are getting stronger and harder as he continues to fight for revenge. Will Sang-Baek’s revenge succeed?