pep rally; send-off ceremony
A formal gathering to encourage and cheer on someone before a competition, trip, or new endeavor. Often held at schools or workplaces.
A pep rally was held at school for tomorrow's match.
We cheered the athletes at the send-off ceremony.
壮行会 is a send-off party or gathering, often less formal than 壮行式, which implies a more structured ceremony.
Compound of 壮行 (sōkō, 'sending off with encouragement') and 式 (shiki, 'ceremony').