Jikuun Eshin served as a monk of the Rinzai sect (the Rinzai school of Buddhism) during the Sengoku and Azuchi-Momoyama periods. Eshin lived from Daiei 2 (1522) to 8/3 of Tenshō 7 (1579). A high-ranking priest, Eshin earned the respect of the Mōri clan of Aki Province along with the Imperial Court and Muromachi bakufu in Kyōto, serving as the abbot of multiple temples.
In 1522, Eshin was born in the Kumagaya neighborhood of the Iishi District of Izumo Province.
In 1530, Eshin attended a ceremony conducted by Mitsufusa Egiku (the abbot of the Tōfuku Temple) and then entered the priesthood at the Ankoku Temple (a sub-temple of the Tōfuku Temple) in Izumo. Egiku resided in the Taikō hermitage on the grounds of the Tōfuku Temple.
In 1536, Eshin returned to Izumo. In 1538, Eshin went to Yoshida in the Takata District of Aki Province to pursue his studies and received instruction from Sakuun Genryū, the abbot of the Kōzen Temple, the family temple of the Mōri clan. Thereafter, Eshin, via Genryū, received the trust of Mōri Motonari.
In 1548, Eshin worked at the Kokusei Temple and the Kōjaku temples which were family temples of the Ōuchi clan, the sengoku daimyō of Suō Province based in Yamaguchi. Thereafter, upon the strong urging of the Mōri clan, Eshin developed relations with kuge, or nobles, who came to Yamaguchi from Kyōto.
In 1550, upon orders of his master, Egiku, Eshin traveled to Kyōto and became the head of the Taikō hermitage. In the spring of 1553, he returned to Aki Province, but, in the ninth month of the same year, Egiku died so he returned to Kyōto to succeed him. Later that year, Eshin accepted Ankokuji Ekei as one of his disciples.
Eshin was deeply trusted by the Mōri clan and, in particular, by Mōri Takamoto. On 3/12 of Tenbun 23 (1554), when the Mōri confronted a final showdown with Sue Harukata, Takamoto sent a letter to Eshin expressing his heartfelt concerns. In the tenth month of 1555, after prevailing at the Battle of Itsukushima and launching the Subjugation of Bōchō (a campaign to seize control of Suō and Nagato provinces), Motonari appointed Eshin to serve again as the abbot of the Kokusei and Kōjaku temples in Yamaguchi in Suō. Eshin traveled to Yamaguchi and, while residing at the Kokusei Temple, worked to revitalize both temples. At the same time, Eshin also served as the abbot at the Kōzen Temple after his former master, Genryū.
In 1558, Eshin traveled to Kyōto and returned to the Taikō hermitage. In 1559, he became the 213th abbot at the Tōfuku Temple. While residing in Kyōto, Eshin provided updates to Motonari with respect to the affairs of the Imperial Court and the Muromachi bakufu. In this regard, a noble named Kajūji Tadatoyo (the former Provisional Chief Councilor of State) appealed to Eshin to advise Motonari to make a donation to Emperor Ōgimachi who, despite his accession to the throne in 1557, could not conduct a coronation ceremony owing to a lack of funds. Acting upon this request, Eshin promptly contacted his master, Genryū, who was in Yoshida in Aki Province and recommended that Motonari contribute funds for the coronation. In the fourth month of 1559, Motonari donated 2,000 kan, or coins, via Eshin. On 1/21 of Eiroku 3 (1560), he donated an incremental amount of 59 kan and 400 mon for clothing, after which, on 1/27, a coronation ceremony for Emperor Ōgimachi was held. Owing to these contributions to the Imperial Court issued several appointments,including to Motonari as the Governor of Mutsu, to Mōri Takamoto (Motonari’s eldest son) as the Master of the Palace Table, Kikkawa Motoharu (Motonari’s second son) as the Governor of Suruga, and Kobayakawa Takakage (Motonari’s third son) as the Vice Minister of Central Affairs. In addition, the Muromachi bakufu appointed Takamoto as the shugo, or military governor, of Aki. Eshin was permitted by the Imperial Court to wear purple vestments traditionally awarded only to high-ranking priests and, together with his master, Genryū, was appointed as the abbot of the Nanzen Temple in the Sakyō District of Kyōto.
On 8/4 of Eiroku 6 (1563), upon the unexpected death of Mōri Takamoto, Eshin presented to Motonari the letters that he had exchanged with Takamoto to cherish his memory. As a memorial to Takamoto, his younger brothers, Kikkawa Motoharu and Kobayakawa Takakage, constructed the Jōei Temple in Yoshida in the Takata District of Aki Province. Given that, during his lifetime, Takamoto had considered building a temple for Eshin, Eshin opened the Jōei Temple. As a result, Eshin assigned the Taikō hermitage to his disciple and the 215th abbot of the Tōfuku Temple, Matani Enkan, and went to Yoshida in Aki.
In the third month of 1569, upon request of Ashikaga Yoshiaki (the fifteenth and final shōgun of the Muromachi bakufu), Eshin, along with Shōgoin Dōzō (a monk at the Shōgo Temple and the son of Konoe Hisamichi) endeavored to mediate peace between Mōri Motonari and Ōtomo Yoshishige (Sōrin). However, neither Motonari nor Yoshishige was inclined to settle differences so the parties could not reach agreement. In the tenth month of the same year, the Rebellion of Ōuchi Teruhiro erupted. After Teruhiro invaded Yamaguchi in Suō, Ichikawa Tsuneyoshi (a retainer of the Mōri clan serving as a magistrate in Yamaguchi) was on an expedition in northern Kyūshū, whereupon those serving in his absence including Naitō Narifuji and Yamagata Motoshige, along with Tsuneyoshi’s wife and over 100 soldiers, in addition to Eshin, holed-up in Kō-no-mine Castle in Yamaguchi. This contingent was further joined by local samurai including Arima Zenbei, Tsumori Suketada, and Terado Tsushima-no-kami, along with substitute priests from the Jōfuku Temple.
On 6/14 of Genki 2 (1571), upon the death of Mōri Motonari, Mōri Terumoto dispatched Awaya Motoshige and Kunishi Narinobu to visit Eshin and request that Eshin recite the gatha (poetic verse of Buddhist scriptures) at the memorial service for Motonari with whom Eshin had a close relationship between priest and parishioner. On 6/20 of the same year, a memorial service for Motonari was held at the Daitsu Temple, the family temple of the Mōri clan in the foothills of Yoshida-Kōriyama Castle. At the service, Eshin recited a verse noting that Motonari had been a worldly intellect over his life of seventy-five years. Eshin also gave him the posthumous name of Hiyori.
Owing to his earlier efforts to procure donations from Motonari for the coronation event for Emperor Ōgimachi, Eshin was highly regarded by the Imperial Court and the Muromachi bakufu. In 1570, and again in 1575, he was awarded with honorary titles of a high-ranking Buddhist priest.
Eshin died on 8/3 of Tenshō 7 (1579) at the age of fifty-eight.