Severe fever with thrombocytopenia syndrome virus (SFTSV), Dabieshan tick virus (DBTV), and Jingmen tick virus (JMTV) are emerging tick-borne RNA viruses that may cause febrile illness in humans. While these viruses are currently being studied worldwide, especially in East Asia, research reports in Japan are limited. Such studies are particularly rare in Okayama Prefecture, requiring urgent research. Here, we attempted to detect these viruses from ticks collected in the Chugoku Mountains, a major mountainous area in Okayama Prefecture, in 2024 using a basic PCR method. Among 95 pooled samples prepared from 1,053 ticks by species, sampling site, and collection date, 47 contained DBTV associated with Haemaphysalis longicornis Neumann, 1901, and 2 contained JMTV in connection with Amblyomma testudinarium Koch, 1844, but no SFTSV was detected. Unexpectedly, an Okutama tick virus (OKTV) sequence was detected in a pool of Haemaphysalis flava Neumann, 1897, and an unknown virus with up to 88.3% sequence homology to SFTSV was identified in a Haemaphysalis kitaokai Hoogstraal, 1969 pool. The S segment of this SFTSV-like virus contained an ambisense gene organization encoding both a nucleocapsid and a non-structural protein and was phylogenetically classified into a different branch from closely related bandaviruses. This is the first report of DBTV, JMTV, OKTV, and a putative novel tick-derived bandavirus in ticks collected in Okayama Prefecture. These findings provide much-needed insights regarding the existence of emerging tick-associated viruses and crucial insights regarding risks of tick-borne illness in this region, which will inform novel strategies for disease mitigation.