Gansaku no Maria

I am currently attending my own funeral - in order to find the person who killed me. Illustrator Yona Kaminaga is summoned to a retrospective exhibition of her mother, Maria Daichi, a genius painter who died young. When she reveals the existence of a painting that her mother left only to Yona, the looks on the others' faces change.. And that night, she is attacked by someone who tries to steal the painting...!? Will the "fake" discover the truth hidden within the painting? (Source: Kodansha, translated)