Phreatic eruptions of volcanoes are very difficult to predict. There have been various reports of precursory phenomena of phreatic eruptions. However, a general understanding of those phenomena is still lacking. Mannen et al. (2018) studied a small phreatic eruption of the 2015 Hakone volcano in Japan with multidisciplinary monitoring. Based on integrated analyses and interpretation of thermal, electromagnetic, geodetic, seismic, and geochemical monitoring together with surface observations, the authors constructed a physical model of the magma-hydrothermal system that caused the unrest and eruption. Such an integrated understanding is essential for the administration to implement mitigation measures. This paper also provides an excellent overview of the geological background and previous volcanic activity of the Hakone volcano, summarizing the authors' long-lasting efforts in volcano monitoring. Finally, the authors discussed the challenges and limitations as well as prospects of mitigation measures by combining the model and extensive review. It is a significant scientific contribution to volcanology and volcanic hazard mitigation. Therefore, the paper by Mannen et al. (2018) is well deserved for the 2023 EPS Excellent Paper Award.