In the magical world of Verdantia, there is a room with four corners. At each corner stands a statue of a guardian that sees in every direction except directly behind itself because of a magical cloak of invisibility that each wears. The cloaks prevent the guardians from seeing anything directly behind them in a narrow cone extending indefinitely from their backs. In the center of the room is a pillar with a precious gem on top. If Yumiko enters the room and wishes to take the gem without being seen by any of the guardians, how can she accomplish this? Provide a short response.
Since the guardians are placed in the corners and each has a blind spot directly behind them due to their magical cloaks of invisibility, Yumiko must utilize the blind spots to her advantage. First, Yumiko has to determine the exact alignment of the guardians to ensure that the invisible cones created by their cloaks intersect at the center of the room where the pillar with the gem is located. 

Yumiko must approach the pillar by walking in a path that keeps her aligned with one of the invisible cones. In this way, she remains in the blind spot of the guardian whose back is to her. As she reaches the pillar, it is crucial that this pillar is exactly in the center of the room and that the guardians are equidistant from it; otherwise, there might be a gap in their blind spots. 

Assuming the conditions are perfect and the pillar is at the convergence of the blind spots, Yumiko can walk up to the pillar while staying within the blind spot of one of the guardians, take the gem from the top of the pillar, and retreat back in the same blind spot. Each guardian will not see her because she remains within the invisible cone extending from one of their backs at all times. This way, Yumiko can successfully take the gem without being seen by any of the guardians.