It is reported that only olfactory stimulation in our five senses is transmitted directly to the limbic system.
A certain smell became a trigger for reviving old memories. – Everyone should have such experience.
Some companies make use of the effect of scent for their branding.
Singapore Airlines is famous for its sent branding. It developed the original aroma and has kept using it for many years.
Also, Hilton Tokyo in Japan uses original aroma produced by Air Aroma Japan.
In the U.S., smell is registrable as a trademark. However, in Japan, smell is not protected under the Trademark Law due to the difficulty of examination.