Plot premise,
protagonist got transported to another world together with the five of his club mates, after being transported to the world the six of them, a group of knights and a sage welcomes them and wants to escort them back to their kingdom for a heroes welcome and a banquet feast, little did they know the great sage is already under control by one of the four demon lords that serves under the great demon lord , the demon lord wants to use the six heroes as a sacrifice to the great demon lord so he can be granted more power, however by the help of the main protags keen senses he dectected the danger early on and manage cook out a plan to escape and defeat the enemies, they discovered that the great sage is one of the demonlords,they managed to barely defeat him but they later discovers that the demon lord was not at full power and is has only possessed the body of the great sage, before the body crumbles into ashes he discovers that despite the talents and skills of the other five the main protagonist is really the one real threat and used every last bit of remaining power os the great sage to transport him to another continent where the heroes are despised by the people, after he wakes up he see's a message that he leveled up from level 1 now he's level 15 now he can use a skill "jack of all trades" which enables him to use all of the skills from the five heroes once per day, however the downside is he will never recover his mana naturslly and will need to drink potion now and then just to fill up his mana gauge, with his wits and intellect he manage to overcome all the hurdles and eventually was able to defeat the demon king all by himself without the five other heroes knowing, after he defeats the demonnking he was greeted by a message that congratulates him however there is an option , Go home and leave the five heroes trapped in the world , or be the great demon king, let them defeat you and send the 5 heroes back home, leaving you trapoed into this world being reincarnated as a real citizen of the world after being defeated as a demon king"