The Ryukyu Long-furred Rat is assessed as Endangered under B1ab(iii) because its extent of occurrence (EOO) is approximately 4,921 km², it is found only on three islands, and because there is ongoing deforestation in its range. It is also predated by introduced species such as feral dogs (Canis familiaris), cats (Felis catus) and introduced mongooses (Urva auropunctata), and may be at risk of road traffic, but the population-level impacts of this are unknown. Research is needed to clarify population status, trends and threat impacts.

This species is found only on Amami-oshima and Tokuno-shima islands of the Amami Group, and Okinawa Island, on the Ryukyu Islands in Japan. Since 1980, the species has been restricted to the mountains in western Amami-oshima, Mount Amagi, Mount Inokawa, and Mount Inutabu on Tokuno-shima, and the mountains in the northern part of Okinawa (Abe et al. 2005), and is typically known from elevations of 300-400 m asl (Fabre 2017). The mountainous areas of these three islands, which are hotspots for this species, were designated as the Natural World Heritage site in 2021 though the impact of invasive alien species (Shionosaki et al. 2015, Maeda et al. 2019, Kobayashi et al. 2020, Yagihashi et al. 2021) and roadkill (Miyamoto et al. 2021) remains a concern.

This is a rare species. Based on questionnaire surveys conducted in 1985 and 1995, the species is thought to have undergone declines. A 5-day survey of droppings and feeding marks in Tokuno-shima Island confirmed presence around several mountainous areas, but did not provide data for determining population status (Jogahara and Koshimoto 2017). On Okinawa Island, a six-year survey counted 75 live individuals and 47 roadkill specimens, though where invasive mongooses had not become established (Tamanaha et al. 2017). Predation from the Small Indian Mongoose (Urva auropunctata) is considered a significant factor in population decline, but since the Ministry of the Environment commenced a mongoose eradication project from 2000 on Amami Island, populations of the Ryukyu Long-furred Rat may have began to recover there (Fukasawa et al. 2013); a similar programme has also been deployed on Okinawa Island (Yagihashi et al. 2021).

The species inhabits intact chinquapin and oak forests from mid- to upper montane regions on Okinawa, chinquapin and oak forests and secondary areas at 300-400 m Asl on Amami-oshima, and areas with over 60% forest cover at elevations of 300-400 m asl on Tokuno-shima (Abe et al. 2005). The species uses tree cavities for nesting and breeding, as recorded in trees of mature forests on Okinawa Island (Takashima et al. 2021, Kobayashi et al. 2022).

There is major deforestation on all three islands, which is of particular concern given that this species uses tree cavities in mature forests that may take over 70 years to recover (Takashima et al. 2021, Kobayashi et al. 2022). Additionally, there have been concerns of disease affecting this species, with the zoonotic nematode Angiostrongylus cantonensis being detected in this species from Okinawa Island (Nakaya et al. 2013, Okano et al. 2014) and Amani-oshima Island (Tokiwa et al. 2020), leading to an infection that may have been lethal (Okano et al. 2014). Free-roaming cats (Felis catus) could be a potential source of other diseases including Toxoplasma gondii (Matsuu et al. 2017, Shoshi et al. 2021, Okada et al. 2022), though evidence of this has not been observed in the Ryukyu Long-furred Rat. There is also extensive documentation of the threat of roadkill to these populations where roads run through key habitat, such as in Yanbaru National Park (Tamanaha et al. 2017). Finally, feral dogs (Canis familiaris) (Watari et al. 2007) and cats (Shionosaki et al. 2015, Maeda et al. 2019, Kobayashi et al. 2020) predate this species on all three islands. The introduced mongoose has reduced the distribution ranges of this species on Amami-oshima and Okinawa, though a mongoose management project commenced in 2000 on both islands. Eradication of the mongoose was then declared by Ministry of the Environment in September 2024 on Amami-oshima Island after a monitoring period of more than six years of zero capture. Management efforts on both islands have given hope of the recovery of populations where these threats are removed (Fukasawa et al. 2013).

Increased habitat protection and control of introduced predators is needed. It is listed as Endangered (EN) in the Japanese Red List (2020). Population and threat monitoring would be beneficial.