There are many forms of stellar explosions that are observed in the Universe, such as supernovae, kilonovae, X-ray bursts, stellar eruptions, etc. Many of these explosions originate from massive stars, which are predominantly members of binary or higher order multiple systems. Therefore the presence of companion stars may play a critical role in the mechanism of the explosion itself, or conversely, the explosion may affect the properties of the companion stars. In this talk, I will review our work on supernova explosions in binary systems, and stellar merger-driven eruptions in triple systems. I will show various examples where our numerical models reproduce the observed properties of some known explosions (e.g. supernova remnant Cassiopeia A, Great Eruption of Eta Carinae). I will also discuss how we can use the observations of stellar explosions to infer the evolution of the binary (or triple) system leading up to the explosion. Dr Hirai is being hosted by Dr Fabian Schneider of the HITS institute (fabian.schneider@h-its.org). Anyone interested in further discussions on specific topics should contact Dr. Schneider to arrange (virtual) follow-up meetings with Dr. Hirai.