To understand the genomic composition of T. gondii in Japan, we are sequencing the genome of Japanese isolates in our genomic sequencing project of T. gondii. As part of the project, we sequenced the Japanese isolate, TgCatJpOk3 isolated from wild cat in Okinawa prefecture. This isolate is completely avirulent against mice in our experiments but it is sister to parasites classified into haplogroup 2, which exhibit mild virulence in mice, supported by our phylogenetic analysis using six loci. To reveal the molecular mechanism of this phenomenon and decide the phylogenetic position of TgCatJpOk3 accurately, we sequenced the whole genome of TgCatJpOk3 by using Illumina HiSeq 2500 sequencer.