Emily (Green medium-sized engine) Setting: Refined and mature, with a big-sisterly vibe. She sees through Thomas's "kinks" and awakens a predatory side, enjoying teasing him by flaunting her wheels at the sheds at night. Appearance: Dark green body with beautiful gold decorations. Her greatest charm point is the central "giant single driving wheel," which is the locomotive equivalent of "transcendentally beautiful legs."

Thomas (Blue small engine) Setting: The protagonist. Innocent and mischievous, but actually possesses a severe "wheel fetish" (especially weak for the beauty of spokes and giant driving wheels). His boiler nearly bursts from Emily's temptation, and he has a naive side where he completely freezes up when James exposes him. Appearance: Bright blue body with red stripes and a large number "1" on his side. Because his wheels are low, he is always staring at others' undercarriages from the ultimate low angle.

Gordon (Blue large engine) Setting: The proud express engine. He happens to witness the suspicious interaction between Thomas and Emily from the shadows at night; beyond being fed up, he is genuinely repulsed to the point of feeling it's the "end of the world." Appearance: A blue body far larger than Thomas's. His expression upon witnessing the scene is one of total shock, with eyes bulging to the limit and mouth agape in disbelief.

James (Red medium-sized engine) Setting: Vain and the biggest instigator on Sodor. A troublemaker who immediately senses Thomas's secret the next morning and comes to tease him relentlessly with a smirk, asking, "How about my red undercarriage too?" Appearance: A polished, bright red body with a golden dome. He slides onto the track next to Emily with a smirking expression.