What became of Hasekura is unknown and accounts of his last years are numerous. Contemporary Christian commentators could only rely on hearsay, with some rumours stating that he abandoned Christianity, others that he was martyred for his faith, and others that he practiced Christianity in secret. The fate of his descendants and servants, who were later executed for being Christians, would suggest that Hasekura remained strongly Christian himself, and transmitted his faith to the members of his family.
Sotelo, who returned to Japan but was caught and finally burnt at the stake in 1624, gave before his execution an account of Hasekura returning to Japan as a hero who propagated the Christian faith:
"My other colleague, the ambassador Philippus Faxecura, after he reached his aforementioned king (Date Masamune), was greatly honored by him, and sent to his own estate, to rest after such a long and tiring journey, where he made his wife, children, servants, and many other vassals into Christians, and advised other nobles who were his kith and kin to accept the faith, which they indeed did. While he was engaged in these and other pious works, a full year after his return, having provided much instruction and a great example, with much preparation, he piously passed on, leaving for his children by a special inheritance the propagation of the faith in his estate, and the protection of the religious (i.e. "members of religious orders") in that kingdom. The King and all the nobles were greatly saddened by his passing, but especially the Christians and Religious, who knew very well the virtue and religious zeal of this man. This is what I heard by letters from the very Religious who administered the sacraments to him, and who had been present at his death, as well as from others." (Luis Sotelo, De ecclesiae Iaponicae statu relatio).
Hasekura also did bring back to Japan several Catholic artifacts, but he did not give them to his ruler, and instead kept them in his own estate.
Hasekura Tsunenaga died of illness (according to Japanese as well as Christian sources) in 1622, but the location of his grave is not known for certain. Three graves are claimed as Hasekura's. One is visible in the Buddhist temple of Enfuku-ji (円長山円福寺) in Miyagi. Another is clearly marked (along with a memorial to Padre Sotelo) in the cemetery of a Buddhist temple in the Kitayama neighborhood at Komyo-ji Temple (光明寺).
Execution of his descendants and servants
Hasekura had a son, named Rokuemon Tsuneyori. Two of his son's servants, Yogoemon (与五右衛門) and his wife, were convicted of being Christian but refused to recant their faith under torture (reverse hanging, called "Tsurushi", 釣殺し) and as a result died in August 1637 (as the lives of Christians were spared if they recanted, these executions indicate that they were steadfast and refused to deny their faith). In 1637, Rokuemon Tsuneyori himself also came under suspicion of Christianity after being denounced by someone from Edo, but escaped questioning because he was the master of the Zen temple of Komyo-ji (光明寺). In 1640, two other servants of Tsuneyori, Tarozaemon (太郎左衛門, 71), who had followed Hasekura to Rome, and his wife (59), were convicted of being Christians, and, also refusing to recant their faith under torture, died. Tsuneyori was held responsible this time and decapitated the same day, at the age of 42, for having failed to denounce Christians under his roof, although it remained unconfirmed whether he was himself Christian or not.
Also, two Christian priests, the Dominican Pedro Vazquez and Joan Bautista Paulo, had given his name under torture. Tsuneyori's younger brother, Tsunemichi, was convicted as a Christian, but managed to flee and disappear.
The privileges of the Hasekura family were abolished at this point by the Sendai fief, and their property and belongings seized. It is at this time, in 1640, that Hasekura's Christian artifacts were confiscated, and they were kept in custody in Sendai until they were rediscovered at the end of the 19th century.
Altogether, around fifty Christian artifacts were found in Hasekura's estate in 1640, such as crosses, rosaries, religious gowns and religious paintings. The artifacts were seized and stored by the Date fief. An inventory was made again in 1840 describing the items as belonging to Hasekura Tsunenaga. Nineteen books were also mentioned in the inventory, but they have been lost since. The artifacts are today preserved in the Sendai City Museum and other museum in Sendai.