Shizuko "Sprocket" Iwasaki's Links
Nikko has known Sprocket since before she was in the gang. She is the only person he trusts to service his car and he would seek her out specifically for the job. He was disappointed to find out that Shizuko had been recruited into a rival gang and was no longer allowed to work on his car. After being unable to find a suitable replacement, he decided to offer her a position at the Speed Demons as their mechanic, allowing her the freedom to work on any cars she wanted. He was delighted when she accepted the offer, primarily for the benefit of the gang, but deep down he knew it was also because he had missed her company in the time she was gone. Ever since she joined, Nii-chan made a subconscious effort to make sure she was eating and looking after herself. Later down the line when she confessed her feelings, he was taken aback and misinterpreted the confession, accidentally rejecting her in the process. This mistake was very quickly rectified and they started seeing each other, eventually getting married. Nii-chan loves his wife so much, going so far as to rescue her from her kidnappers, wiping out an entire gang in the process. He would never admit it, though, full knowing his wife would go on a rampage.
Rider is absolutely obsessed with Sprocket, as she is technically his mother. Initially, when he was made, he wanted to spend every waking moment with her, much to the detriment of Sprocket's marriage. But after imprinting on Takeshi, he only really talks to Sprocket when she needs help or he when he finds something useful in the scrapyard.