There has been much discussion around the Linguistic-Savings Hypothesis (LSH), which postulates that language can affect intertemporal choices of its speakers; the validity of this claim has remained controversial. To test the LSH independent from the possible influencing factors, such as cultural differences, we focused on the Japanese language, which features asymmetric tense marking, in that past tense is grammatically marked but future tense is not. Adopting a within-participant design, we compared the discounting behavior between past and future gains in native Japanese participants. Our results revealed that Japanese speakers tended to discount the values placed on rewards in an asymmetry way: to discount the value of past gains more heavily than that of future gains. We believed our results corroborated the LSH and linguistic relativity.