Note however that in the case of the Takamatsu Tumulus in Nara Prefecture, although the keyhole tumulus itself was designated a 'special historical landmark' as per item two of Article 109 of the abovementioned law, the wall paintings inside the stone chamber were classified as paintings and designated a national treasure.
ちなみに奈良県・高松塚古墳の場合は古墳自体は同法第109条第2項に基づき「特別史跡」に指定され、石室内の壁画が「絵画」として国宝に指定されている。