Miura reprised his role as Jesse for The Confidence Man JP: Episode of the Princess. In March 2020, he was cast as Hiroyuki Ishimura in the television drama Gift of Fire, which was set to broadcast in August 2020, and reprised his role for the series' film continuation. In the same month, he released his fifth photobook, Nihonsei, in two different versions, with one version including a documentary photobook. He co-starred in the Japanese stage production of Whistle Down the Wind as The Man, which ran from March 7 to April 23, 2020. On his 30th birthday on April 5, 2020, he revealed on an Instagram live-stream that he was releasing "Night Diver" as his second single in early Q3 2020, which contained three songs from different genres including a dance song and a love song. He also stated that he composed and wrote the lyrics for "You & I", one of the B-side tracks, and "Night Diver" was later set to debut on Music Station on July 24, 2020. He was set to have his first concert events in Q4 2020, but they were cancelled due to the COVID-19 pandemic and were planned to be live-streamed instead. He co-starred in the television drama Love Will Begin When Money End, which will be broadcast in September 2020, and was also cast in the musical The Illusionist, which was set to run in December 2020.
On July 18, 2020, at 1:35 pm (JST), Miura was found unresponsive after hanging himself in his closet at his home in Minato, Tokyo. His body was discovered by his manager, who had been ready to pick him up for work and then checked up on him after he did not respond to the messages, phone calls, or doorbell sounds. He was rushed to the hospital where he was pronounced dead at 2:10 pm. Police believe Miura died by suicide, as an apparent suicide note was found in his room. The note, which was written in Miura's notebook, was undated, but he expressed anxiety and thoughts about dying. Miura's friends have stated he showed no signs of being suicidal prior to his death. Media news outlets linked it to cyberbullying and hate comments on social media, but Miura's friends and colleagues partially or completely refuted the claims.
NHK reported on July 20, 2020, that Miura's funeral and burial services had already been held. While fans paid tribute to Miura by leaving flowers outside of his condominium, his agency, Amuse Inc., announced that they will be setting up an opportunity for fans to pay respects while taking in consideration the COVID-19 pandemic. After the official website for Sekai wa Hoshii Mono ni Afureteru: Tabi Suru Buyer Gokujō List, the travel program Miura had co-hosted since its first broadcast in 2018, posted a statement offering condolences to Miura, this led many users on Twitter to tweet messages addressed to him using the hashtag "SekaiWaHoshiiMonoNiAfureteru" (#世界はほしいモノにあふれてる).
Miura's second single, "Night Diver", was released posthumously on August 24, 2020, with it pre-released digitally on July 25, 2020. Gift of Fire and The Illusionist, two upcoming projects that Miura co-starred in, were put on hold. Miura's debut single, "Fight for Your Heart", re-entered the music charts, peaking at No. 7 on Oricon Daily Singles Ranking.