| High-redshift supernovae (SNe) are important probes of stellar evolution in the early Universe. They can provide constraints on stellar evolution in the low-metallicity environments that play a critical role in shaping the compact remnant mass distributions observed by gravitational waves. In particular, pair-instability SNe (PISNe), theorized explosions of massive stars leaving neither neutron stars nor black holes, are predicted to exist exclusively at low-metallicity environments. No PISNe, however, have been conclusively identified. In this talk, we first introduce our high-redshift SN survey conducted by Subaru/Hyper Suprime-Cam (HSC) and discuss our high-redshift SN discoveries so far. Although we discovered several high-redshift SNe up to z = 2.4, we did not find any PISN candidates. In order to discover PISNe at high redshifts, it is ideal to conduct transient surveys in near-infrared because of redshift. I will discuss high-redshift transient surveys with two upcoming wide-field near-infrared observatories, Euclid and Roman. We argue that Euclid will be able to discover dozens of PISNe up to z ~ 3.5. Utilizing redder bands, Roman will allow us to observe PISNe at even higher redshifts back to the Epoch of Reionization—up to z ~ 7. Through high-redshift SN discoveries, Euclid and Roman will revolutionize our view on massive star death in the early Universe. |