The Mirror of Nothingness

Seven strangers, each of whom had never met before, received a strange invitation with no signature, and were led to the deserted Twilight Mansion on the outskirts of the city to attend the 60th birthday of the owner, Shen Yuzhou. The candlelight at the birthday banquet was dim, and Shen Yuzhou looked around the banquet, and his color suddenly changed. He clearly sent eight invitations, and there were supposed to be eight guests at the banquet, but there were only seven living people at the table. The eighth visitor was mysteriously absent. Someone whispered a strange method: move out the rusty ancient mirror in the old house, have one person sit and dine in front of the mirror, and fill the empty seats with the shadow in the mirror. But if someone really sits in front of the mirror, is the person who comes to take the seat a reflection, or is it something trapped in the mirror?