Legato is Count Waltz's right-hand man and is arguably the secondary antagonist in "Eternal Sonata". He has no problem serving Count Waltz, even though Waltz is only 16 years old.
At the beginning, Legato was seen in the Forte Castle Throne room speaking to Count Waltz about what is going on with a battle against Andantino. He was also talking to Salsa about the Mineral Powder. Discovering that she was a guardian of Agogo Forest, he has the guards throw her in the dungeon. Later, he also informs Waltz about Tuba's death involving Cabasa Bridge, though Waltz didn't care at all.
At Mt. Rock, Legato and Count Waltz rode to the summit with an army of dragons to neogiate with Cresendo and Serenade. Also, to retrieve Polka for the agogo to glow. When Polka chose to come with them, Allegreto tries to stop her, only for Legato to stop him instead. After the skirmish with Count Waltz, he deliberately orders Legato to drink the new and improved medicene. Legato then transforms into an incredibly powerful monster named "Ruined Body". He demonstrated his powers by wiping out their own army of dragons. Just as when Legato was about to kill everyone else, Polka's astra shined and reflected his power, causing it to rip a hole in space. Jazz implied that they ran away on the other side.
On top of the Double Reed Tower, Count Waltz and the new and improved Legato were seen together. After talking to the group for one last time, they decided to defeat everyone else for good. In the penultimate battle, in the Xbox360 version, Legato fights alone. However, in the PS3 version, he and Count Waltz are fought together. Afterwards, Count Waltz gave his final orders to Legato: to "TEAR APART THIS ENTIRE PATHETIC WORLD!!!" He and Waltz were both killed in the blast, never to be seen again.
- He was voiced by both Chafurin in the Japanese version and Jamieson Price in the English version.