Recently, new genotypes of human adenoviruses (HAdVs) have been reported and many of them have been found to be recombinant forms of different known types of HAdV species D (HAdV-D). The objective of this study was to document the evolutionary features of a novel isolate (HAdV_Chiba_E086/2012) obtained from the eye swab of a patient with conjunctivitis in Japan. Viral DNA was extracted from the isolate to sequence the whole genome by the Sanger method and aligned with available genome sequences of HAdV-Ds. The phylogenetic trees of the nucleotide sequences of the penton base, hexon, and fiber genes and the E3 region showed that HAdV_Chiba_E086/2012 is closest to HAdV genotype 65 (HAdV-GT65), HAdV-48, HAdV-GT60 and HAdV-22 at 98%, 99%, 95% and 98% identity, respectively, suggesting that this isolate is a novel recombinant form to be designated as P65H48F60. Further phylogenetic and recombination analyses of the genome alignment of the new isolate implied that nested recombination events involving HAdV-GT59, GT65, 48, GT60, 22, and some ancestral lineages or their close relatives have shaped its genome. These results showed that HAdV_Chiba_E086/2012 is the first HAdV-48-related HAdV found in Japan, which has the most complicated evolutionary history among the known HAdVs so far.