|Full name||Kaga Ryosuke|
|Eye color||Olive Green|
Ryosuke Kaga (加賀 良介 Kaga Ryōsuke?) is the main protagonist of the story. He's a perverted second-year student at Momozomo Academy who uses his perverted spirit-energy to give Lisara energy. He also learns from Lisara that he will die in three months, and it is in exchange for his help that she tries to alter his fate. Lisara uses the Broken Sword, Gram, which used to belong to the God of War, to form a contract with Ryosuke. However, it was revealed later that Ryosuke has the other half of Gram (which was thought to be lost), thus gaining full power of the sword. He is in love with Lisara, and can only fully charge his perverted spirit energy if it is her body alone or with his "Invisible Dictionary." He lives all by himself (until Lisara moved in) while at the meantime his mother works overseas in Germany and sends him money from time to time. His mother told him that his father died when he was a kid, however this is a lie. His father is actually alive, and he left with no trace and his mom, not wanting to hurt him; lied about his dad dying.
Average height of the male characters shown and has dark hair. He has dark green eyes and usually wears a the boys uniform
Ryosuke is a very perverted boy who often finds himself at odds with girls due to his outrageous comments (many of which he accidentally mumbles while thinking to himself). However, his erotic thinking is actually what drives him to being a person who truly cares about the well-being of all girls. He considers them as "treasures" and vows to protect all girls.
- Charge up his energy by getting aroused (It seems that there is more energy when he is aroused from Lisara).
- Holder of both parts of the legendary sword Gram, one given by his father before his birth, the other by Lisara.
- The Invisible Dictionary: after many days and nights memorizing words and word definitions from dictionaries, Ryousuke have developed it's ultimate ability to quickly flip to any page of his invisible dictionary, and be able to "read" a specific word's definition, then associate that with something erotic and almost instantly recharge his energy, being capable of using this technique multiple times in a row for a massive supply of energy.
Only a few people that are close from Ryousuke can see his Invisible Dictionary, and he takes a centaur or angel form while reading it for those who can see it.
The pleasures of this world are varied and often come with a price, which is something Ryosuke Kaga learns far too late. After foolishly agreeing to share his "essence" with a dying woman who turns out to be the Goddess of Death, Ryosuke realizes that his pact with Lisara Restole carries a hefty toll... not on his life, but on his lecherous spirit! His only choice is to help Lisara achieve her goal, thus freeing himself from her clutches and regaining his ability to enjoy the more licentious parts of life.
- He is voiced by Hiro Shimono in Japanese dub & voiced by Max Mittelman in English dub.
- His mother is named Saotome Kaga.