In a large room partitioned by opaque dividers, there is a gathering of four friends: Keiji, Lina, Amare, and Yara. Keiji and Lina are standing on one side of a partition, and Amare and Yara on the other. Everyone is evenly spaced from the dividers. The dividers do not reach the ceiling, leaving a small gap between the top of the partitions and the ceiling itself. Initially, no one can see each other because the dividers block their line of sight. Keiji, who is taller than the partition, can peer over the top if he stands on his tiptoes. Yara, who is of average height, cannot see over the partitions even on tiptoes, but she has a hand mirror with her. Suppose Keiji decides to stand on his tiptoes to see if he can spot his friends on the other side and Yara, at that exact moment, decides to use her hand mirror to check if she can see over the partition by angling the mirror to reflect the space on the other side. What, if anything, will Keiji and Yara see regarding the other people in the room? Provide a brief response.
When Keiji stands on his tiptoes, his additional height allows him to peer over the top of the partition. From this elevated perspective, he will be able to look down onto the other side of the partition. As a consequence, Keiji will have a clear line of sight to Amare and can see his head and shoulders, assuming Amare is not standing too close to the partition and within Keiji's angle of view. Keiji can also potentially see Yara's head if she is standing at a distance from the partition where her head is within his field of vision.

Yara, on the other hand, has a mirror at her disposal. By holding the mirror at an angle, she can reflect light from one side of the partition to the other. However, Yara's ability to see anything useful with the mirror depends on the angle she holds it at and her distance from the partition. If she holds the mirror high enough and angles it properly, she may be able to catch a reflection of Keiji's face if he is peeking over the wall at that time. This would be possible because the gap between the top of the partition and the ceiling allows for light to travel over the partition, and the mirror can then redirect that light into Yara's eyes, forming an image. However, she is unlikely to see Lina, who is too short to be seen over the partition, unless Lina is also using a method to elevate her height.

Both Keiji's and Yara's visual access to the other side of the partition rely on their respective positions, the angles at which they are attempting their viewing strategies, and the timing of their actions. If Keiji is tall enough and is currently looking over the partition at the same moment Yara angles the mirror correctly, they could potentially see each other--Keiji directly and Yara via the reflection in the mirror.