red team
Refers to a team designated by the color red, commonly in school sports days or the NHK Kōhaku Uta Gassen (Red vs. White song contest).
See also: 青組 (あおぐみ)
At the sports day, I was on the red team.
The cheering squad for the red team was really fired up.
Standard kanji spelling; 紅 is the more specific character for 'crimson' and is commonly used in the context of the NHK Kōhaku Uta Gassen.
Alternate kanji spelling using the more general character for 'red'; also seen in school sports day contexts.
Compound of 赤/紅 (aka, 'red') and 組 (kumi, 'group, team'). The reading あかぐみ is a straightforward combination.