With the needs of consistency between multiple datacenters for state management in transaction processing system, multi-datacenter synchronization is required, both for reducing response time and for providing fail-over in the event of disaster. However, in synchronization, prioritizing consistency causes latency degradation, while preserving response times may cause data inconsistencies, both of which are unacceptable. Therefore, we propose a synchronization method with two characteristics: prioritization of identifier transmission along with transaction identifier, and replication status verification prior to access. By applying the proposal to prototype in-memory KVS, we verified the response time degradation can be reduced while eliminating potential of conflicts.