A-rank obtainment difficulty.

That magic is extremely advanced.

I'd say the difficulty for this mission is D-rank.

Marimo-chi A super-fast ball-like creature about as hard as rubber. Deals little damage, but can be annoying if it smacks you in the face. Look carefully. Its difficulty to obtain is ranked D.

But the game has a low difficulty rank on the Hunter site's treasure list.

That's due to the card's difficulty to obtain and the card transformation limit system.

even if you devote your whole life to it.

It's an extremely difficult spell that gathers and concentrates sunlight and moonlight.