Tsuna's father, supposedly working at oil fields, rarely sees his family. Iemitsu is the great-great-grandson of the first Vongola boss. Tsuna considers him a loser who has nothing to do with the Mafia, but Iemitsu is actually a key figure in the Mafia world. Though not officially part of the Vongola Family, he holds the position of "Outside Advisor," the second highest rank after the boss during family crises. After Vongola IX chose Xanxus as his successor, Iemitsu, who wanted Tsuna to become the next boss, protested. He traveled around the world while waiting for the 9th's response.
He returned to Japan with Dino and brought the real halves of the Vongola Rings. To keep this a secret, he instructed Basil, his subordinate and disciple, to deliver the fake halves to Tsuna (though Basil was unaware they were fake) to act as a decoy. Despite using him as a decoy, both Reborn and Dino believed it was the right decision. Basil remained loyal to him throughout.
During Tsuna and his family's training, Iemitsu secretly watched over each one of them. During the battle for the Vongola rings, Iemitsu believed that the IX was dead. He went to Italy with his subordinates to verify his suspicions. When he found what appeared to be the IX, it was revealed to be a fake.
In the Future arc, Iemitsu and his wife are currently on vacation in Italy. Iemitsu usually carries a pickaxe around. He was once known as the Vongola's "Young Lion."
