Nazeka Tsukaima no Usagi wa Boku wo Dekiai shisugiteru

Aidan McGuire is a new wizard of the "Guardians of the Order" that protects the country. Guardians are usually paired with a humanoid familiar, so summoning one is essential. However, Aidan, who has zero sense of magic, ends up summoning an adorable rabbit! What's more, he is told that in order for a familiar to unleash its true power, deep contact is necessary...So when he tries to kiss it, the rabbit disappears, and instead a young man who calls himself "Jougasaki Hidetora" appears!? A fantasy BL story set in another world featuring a cute (!?) familiar buddy with a secret and a wizard with vague memories of his past life!

(Source: Kadokawa, translated)

Note: Includes two extra chapters.