The crest of Ryoma SAKAMOTO's family has bellflowers at the intersections, but since the crest when the family name was Ohama, before it became SAKAMOTO, had a 田 character with a circle, there is no relation to the Akechi clan.
なお、坂本龍馬の坂本家の家紋は組み合わせ角に桔梗だが、坂本姓以前の大浜姓の頃の紋は丸に田の字なので明智氏との関係はない。