company initiation ceremony; welcoming ceremony for new employees
Refers to the formal ceremony held by a company to welcome new hires, typically in early April.
The initiation ceremony is held on April 1st.
The new employees were nervous at the welcoming ceremony.
Means 'joining a company' as an act; 入社式 is the ceremony for that occasion.
Compound of 入社 (にゅうしゃ, 'joining a company') and 式 (しき, 'ceremony').