This is set 2 years before zenitsu meets nezuko Inosuke gets a leg injury and he is ordered by his coach to go to a doctor where they found out he had ripped the tendon in his knee and he would require surgery and physical recovery. He would also be sent to a rehabilitation center after the surgery as his injury would take several months to a year to completely heal. He is very against all of this that is untill he meets someone very special