Imagery of butterflies
Butterflies are mostly shown in relation to human soul. When a butterfly appears it is a sign of death as the soul of someone will leave their body or a soul of a deceased is visiting in the form of a butterfly. This is stated in the Insect Study of Butterflies. In the story Dream of Akinosuke the main character falls asleep and dreams of being married to the king's daughter. In the end of the story we find out that his soul left his body in the form of a butterfly and he lived those few moments he dreamt in the nearby ant hole.
Tree imagery
Tree imagery appears to showcase human relationship with nature. Trees are thought to have a soul of their own and destroying them means death of that soul. This is literally shown in the story of Aoyagi where the girl Aoyagi is a personification of a willow tree and when that tree is destroyed she dies.
Imagery of night
Given that this is a collection of mostly ghost and somewhat scary stories, the imagery of night is no surprise. In the first story Mimi-Nashi Hoichi Hoichi gets taken away by ancient spirits during the night. In Jikininki traveling priest Muso witnesses the entity feeding on the dead body during the night. Mujina is a story about encounters with faceless people and those encounters happen at night. Night creates the atmosphere for upcoming scary and ghostly events.
Imagery of bodily grotesque
This imagery serves as a psychological tool to further showcase the bizarre qualities of these stories hence the title containing the word strange. This imagery creates an uneasy feeling as it is closely related to the readers because most humans are empathetic creatures. Bodily grotesque appears in the stories Mujina where faceless people are shown, Rokuro-Kubi where heads that can function without their bodies appear, Diplomacy...