Personality Exchange

Personality Exchange (人格入れ替わり) is the first supernatural phenomenon caused by Heartseed and is featured in Hito Random. Later, in Asu Random I  the Track & Field Club is plagued by this phenomenon.

Description
Members of the group exchange personalities (trade souls, essentially) at random between each other and at random times. Any combination of exchange is possible, such as 3 people switch or all 5 switch at the same time. Each exchange can potentially last from a few minutes to a few hours.

Initially, exchanges would leave the members briefly fazed, often leading them to collapse on the spot. However, after several switches, the members are no longer prone to collapsing and can immediately react to their exchange.

As revealed by Heartseed, should a person die while their personality is switched, the soul that is currently inhabiting the deceased will die with the body.

Trivia

 * Briefly collapsing as a result of switching was left out in the anime.
 * In the English Dub, this phenomenon is referred to as "Personality Swap".