意気揚揚
i.ki.you.you

Literally: mind/heart – spirit – raise – raise

Alternately: In high spirits; triumphant, elated… by extension, boastful; proud unto arrogance; full of oneself. Often used with the ironic or critical nuance that someone’s inflated self-esteem is not actually in keeping with what they deserve.

Notes: This phrase comes to us from our friend, the Records of the Grand Historian (Japanese 『史記』 = Shiki).

As usual, the doubled character may be replaced with a doubling mark, 揚々. Some versions may also use homophone 洋 (again, as either 洋洋 or 洋々) but this character means “ocean” so I wouldn’t recommend it.