The Dutch left-back and and French winger have returned to Vitesse Arnhem, while Eden Hazard's younger brother will go back to last season's surprise packages in Belgium
Kakuta and Van Aanholt have spent pre-season training with Vitesse, and both featured as the club finished second to Ajax in the Eredivisie last term.
Chelsea and Vitesse enjoy a close relationship which helped the Blues tie up a deal for star midfielder Marco van Ginkel earlier this summer.
Hazard, the younger brother of Eden, shone for Zulte Waregem as they mounted a surprise challenge for the Belgian title last season, narrowly losing out to Anderlecht on the final day.
The 20-year-old earned his first senior call-up for Belgium in May, replacing Romelu Lukaku in the second half of a 4-2 victory over the USA.