With the preliminary goal of fissile-nuclide content quantification in small samples containing uranium and plutonium, the Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) of the Japan Atomic Energy Agency (JAEA) is developing the Delayed Gamma-ray Spectroscopy (DGS) non-destructive assay technique. For this, while in the past years several experiments were conducted to prove the feasibility of the technique, a new instrument was design considering the previous lessons learned. It includes a modular insertion for different neutron sources, as radioactive sources or neutron generators; a gamma-ray detector with improved data acquisition system allowing for real time dead-time correction; a full new mechanism for the sample transfer between irradiation and measurement. Together with this, neutron detectors are integrated to supplement the DGS analysis and monitoring the source intensity. In this work, we will describe the new instrument and the preliminary results obtained from instrument characterization compared to previous experiments.