Sayaka Yumi has appeared in several other series in the Mazinger franchise, often as a companion of Koji Kabuto. This page is for her appearances that are similar but do not seem to fit with other series.
Sayaka appeared piloting the Aphrodite A battling the Mechanical Beasts with Koji and Mazinger Z. She was also there when Koji challenged Akira Fudo to a race and was kidnapped along with Shiro by Sirene. They were saved by Devilman and later saw Mazinger Z defeat the rest of the Demon Tribe and Dr. Hell.
Sayaka was enjoying her time with Koji with the battle with Dr. Hell over. However, the free time was cut short when the Warrior Beasts began to attack. Sayaka piloted Diana A to protect the Photon Lab until the Warrior Beast Dante broke through the barrier and easily defeated her robot. When Shiro was injured, Sayaka contacted Koji over radio about the incident. When Koji returned, she urged him not to give some of his blood to Shiro since he lost a lot in the last battle but Koji doesn't listen and the transfusion goes through. When Koji found out about the Mycenae Empire and that Shiro survived, Sayaka overheard his resolve to fight and realized she could not stop him. Before Koji left, Sayaka gave him Shiro's present before leaving in tears. She was overjoyed upon hearing that Koji survived because the Great Mazinger.
Sayaka was vacationing in Paris with Koji, Lori, Loru, and Dr. Morimori before seeing the Great General of Darkness appear as a projection to announce the empire's attack. Sayaka stays by Koji's side throughout the journey back to Japan while encountering the Empire which took the lives of Lori, Loru, and Dr. Morimori. Back in Japan, they attempt to get back to the Photon Lab with help from a trucker named Riki. However, Archduke Gorgon was still on their tail having survived their last encounter. Sayaka attempts to draw him away from Koji by riding on a motorcycle and is knocked unconscious as a result. With Sayaka out cold, she is left in Riki's care where she watches as Koji pilots Mazinkaiser and defeats the Great General. Sayaka attends the funeral for Lori, Loru, and Dr. Morimori before helping rebuild the lab.
When Mazinger Z was hijacked by the Kedora, Sayaka piloted the Hover Pilder to help Koji recover it. They encounter the Garadoubla MK01 along the way before managing to get the Kedora off Mazinger Z where it later hijacked Garadoubla before watching Koji and Mazinger fight it off.
Sayaka goes to Koji after he spent some time with the remains of Mazinger Z. She shows him the rebuilt and upgraded Aphrodite A telling him that she'll be ready to fight again. Koji only tells her not to as he won't be there to protect her. Sayaka looks at him with concern as Koji leaves.
Sayaka in Diana A with Jun Hono and Venus A were beaten from the attack by the Pikadron robots. As Michiru Saotome gets them away from the battle zone, Sayaka could only watch as Mazinger Z protected the Great as it was thrown into the ocean by an enlarged Pikadron. While Mazinger was recovered, Koji was nowhere to be found. Sayaka and Shiro cried at the possibility of Koji being dead until Prof. Yumi told them to focus on the problem at hand. Sayaka was overjoyed when Koji turned up alive in the Double Spazer. Before he went out, Sayaka gave him his older pilot suit since his new one did not suit him.
While Sayaka did not have a speaking role, she was seen in a few screenshots in the background as Varon began his attack.
Sayaka piloted a new robot called Aphrodite A Neo to fight the Mechanical Beast Zetsurion H69 and despite having the advantage in speed and agility was overpowered and pinned down. Koji piloting Mazinger Z rescued her and destroyed Zetsurion, gloating Koji offered to help Sayaka up. She refused and angrily walked off. At the school's showers, Sayaka is asked how her relationship with Koji is going. She replies that because of the multiple attacks by the Mechanical Beasts, they haven't had much time to date let alone say "I love you". Baron Ashura later appears and puts all the girls to sleep as part of his plan to hold them hostage with the Mechanical Beast Gargle RD7. Mazinger Z came to fight it, until noticing that Sayaka and girls from his school were being held hostage. While Mazinger managed to free some of them, Ashura had Gargle show off Sayaka's private areas in front of Koji which distracted him and caused Mazinger to be knocked around. Sayaka grew concerned for Koji before her father and Boss's gang showed up with Aphrodite. With Ashura distracted, Sayaka boards Aphrodite to help Mazinger destroy Gargle. With the battle over, Koji proceeds to have Mazinger restrain Aphrodite to look at the still naked Sayaka, much to her embarrassment.
Sayaka watched as Mazinger Z was overpowered by the gigantic Kekko Kamen. When the Iron Masks attacked the Photon Lab, Sayaka used Kekko Kamen's tactics to defeat them by stripping naked and using her body to distract them as she overpowered them.
Koji and Sayaka were transported to the future in a lab accident in the Photon Lab where they encountered a human resistance to the Creatures, robots that dominated Earth. Sayaka with help from Miku brought back allies from the past to help fight including Great Mazinger, Diana A, Venus A, and Getter Robo G. Sayaka piloted Diana A in the battle against the multiple enemy armies composed of the creatures and past enemies.