Quick answer — Hayato Fujii voices Duston in Fate/Grand Order Absolute Demonic Front: Babylonia, Gurd in The Wrong Way to Use Healing Magic, Loris Cariello in The Unwanted Undead Adventurer and 5 more characters.
Hayato Fujii voices Duston (Fate/Grand Order Absolute Demonic Front: Babylonia), Gurd (The Wrong Way to Use Healing Magic), Loris Cariello (The Unwanted Undead Adventurer), Kogou (So I'm a Spider, So What?), Kanigawa (Malevolent Spirits: Mononogatari), Katou (KOKKOKU), War Wolf (I May Be a Guild Receptionist, but I’ll Solo Any Boss to Clock Out on Time), Sanshirou Toumi (Code Geass: Rozé of the Recapture).
Duston is voiced in Japanese by Hayato Fujii.
