Noun, Suru verb, Intransitive verb, Noun which may take the genitive case particle 'no'
1. belonging to (a group, organization, etc.); affiliation (with); being attached to; being under the control of; serving (in the military, congress, etc.)
My older brother was an active marathon runner as a student and won a major national championship. After graduation he continued his competitive running career while working in the corporate world.— Jreibun