expression, noun
feeling extremely happy; in seventh heaven
Idiomatic expression describing a state of overwhelming joy or elation, as if one were ascending to heaven.
合格通知を受け取ったときは、天にも昇る心地だった。
When I received the acceptance letter, I felt like I was in seventh heaven.
有頂天 also means ecstasy or being overjoyed, but it often implies being carried away or losing oneself in happiness, while 天にも昇る心地 focuses on the sublime, elevated feeling itself.
The expression literally means 'a feeling as if rising to heaven', a metaphor for extreme happiness. The exact origin is uncertain, but it is a natural extension of the imagery of heaven as a place of ultimate bliss.