This paper concentrates on parallel queueing systems, called fork-less shaped queueing systems, taking a checkout area of the supermarket as an example. In fork-less shaped queueing systems, customers choose the server with their criterion. Sometimes queue length become imbalanced due to customers freely choices. Imbalanced queue has negative effects on both store clerk and customer, so it is necessary to reduce the variation of queue length. “Shikake” is a method of changing human behavior. It can be possible to reduce the variation of queue length. In this paper, we suggest some reduction Shikake and verify the effects of them using a multi-agent simulation.