time travel (The further back you go, the younger you get. To distinguish from time travel where the age remains the same as before the trip.)

to time travel

to change, to make different / to move or shift to a different time or place

to use / to employ / to make use of, to apply / to spend

potential of 変える (kaeru): to be changeable / passive of 変える (kaeru): to be changed

the past (period of time that has already happened)

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

to return / to go back / to come back