Connection system, plug, and substrate member

A connection system comprising:

• a plug including:
• a plurality of conductors each extending along a first direction;
• a plurality of terminals each electrically connected to a corresponding conductor among the plurality of conductors, each of the plurality of terminals extending along a second direction;
• and
• a first housing holding distal end portions of the plurality of conductors and the plurality of terminals, the first housing including an end surface intersecting the second direction;
• and
• a substrate member including a first substrate, wherein the first substrate includes a first main surface facing the end surface of the first housing in the second direction and a plurality of electrode pads disposed on the first main surface, wherein
• the plurality of conductors are arranged side by side in a third direction intersecting the first direction and the second direction, and the plurality of terminals are arranged side by side in the third direction,
• the plug is attached to the substrate member, and
• each of the plurality of terminals includes a distal end portion facing the first main surface on the end surface of the first housing and configured to come into contact with a corresponding electrode pad among the plurality of electrode pads in an elastically deformed state.