Lewis is a narrow gauge military tank engine.
Lewis was originally built for the British War Department Light Railways for service in France during World War I. After the war, he was found by the Representative and brought to Keikan Island. He worked on the narrow gauge logging railway on the west side, until he was purchased by the Mainland's military and officially moved east in 1936. He was used for the transportation of soldiers, weapons, machines, and wastes to and from the military base. As the base was near the Lower Valley Railway, the Small Controller would occasionally loan him to work when no other engine was available.
Lewis was also responsible for the Great Harbor Fire in 1956, when he damaged some trucks filled with waste, causing them to catch fire. He was then forced to stay at the harbor for several years to help with repairs. In 1951, he assisted with the rescue of Morning Light. In 1954, he discovered Kudo hidden in a shed, and brought them to the Lower Valley Railway to have them repainted and repaired.
When the mine diesel Joel failed in 1956 and was sent for an overhaul, Lewis was employed to work at the Wild Rock mine, though would sometimes assist on the Lower Valley Railway. But when he deliberately disobeyed direct orders from his superior officer, and instead rescued Smudger from a collapsing mine shaft, he was locked away in his shed. Luckily, he was purchased by the Little Controller in 1958.
Lewis is easily described as "thick-headed". He thinks he's the best engine on the whole railway, and won't let anybody tell him different. He has a sharp tongue and tends to bark orders at other engines. He's also known for his inability to question authority; he'll automatically do what he's told without a second thought. What Lewis lacks in his imagination and grace he makes up for with his hard work and determination. Kudo and Yume show respect for him after he rescued them, but Candy detests him. Lewis has a bad habit of assuming Candy is incapable of work, and often tells her to leave the hard work to "the big, strong engines". Candy, however, is more clever and creative, and has gotten back at Lewis many times.
Lewis is based on the Baldwin Class 10-12-D, identical to Stanley of The Railway Series.
Lewis is painted brown with dark green stripes.