hero organization

in this world their are hero's with different ranks that range from rank E,E+,D-,D,D+,C-,C,C+,B-,B,B+,etc to rank SSSSS+ the organization helps to deal with portal gates, which has loads of 1 race of type of monsters, nobody knows how these portal gates started but they have different rankings from blue, orange, red, grey and black, from rank E to C+ are only allowed to do blue rank portal gates while ranks B to SS+ can do from blue to grey portal gates while SSS to SSSSS+ can do all portals, all humans have a power that helps them fight, some can summon spirits which are also ranked from E to SSSSS+ to help them. some people form their own groups while others prefer to go solo, when a gate is cleared it turns green, but when a gate locks itself because of the boss it turns red, the gates can change color after some hero's enter. their are guilds and other people who aren't cut out to be a hero so they have normal jobs