Kaku is currently staying with the Rams on an initial one month agreement but has so far has been unable to make much of an impression during his stay at Pride Park.
He was left out of the Derby team against Coventry City on Saturday with manager George Burley putting his absence down to a virus.
Rumours circulated that the African was back training with Bolton, but Derby's Director of Football Murdo Mackay explained that Kaku will remain with them until the end of this month at least.
"The player is on loan for a month and will see out the loan period, unless there are extraordinary circumstances."