Manyika made his first international appearance representing Zimbabwe U19 at the 2007 Under 19 Rugby World Championship in Belfast, Ireland. Upon leaving Harlequin F.C. he went on to play for the Zimbabwe national rugby sevens team in the World Rugby Sevens Series, winning the Bowl final at the 2009 Rugby World Cup Sevens in the United Arab Emirates. Manyika played a total of seven matches for the Zimbabwe national sevens team, scoring a total of 20 points (2 tries and 5 conversions).