Kamen Rider Black RX was the first Kamen Rider to have multiple forms: Robo Rider and Bio Rider. The concept of "multiple form changing" Riders would be repeated throughout the Heisei Kamen Rider series. Form changing is best described as alternating back and forth between forms to adjust to different situations. In his base form, Black RX is a photosynthetic warrior as well as the evolved form of Black using the sun as his main energy source. When Kohtaro becomes Black RX, he says, "I am the Child of the Sun! Kamen Rider Black RX!" (俺は太陽の子！仮面ライダーＢＬＡＣＫ ＲＸ！ Ore wa Taiyō no Ko! Kamen Raidā Burakku Āru Ekkusu!?) While in this form, Black RX uses his Macro Eye to detect his opponents' weaknesses, hidden objects, or people behind any obstacles. His signature weapon is the Revolcane sword and can perform his dropkick Rider Kick called the RX Kick (ＲＸキック Āru Ekkusu Kikku?).