(called "sphere pools") that serve as the playing field for blitzball games. The pyreflies are also a source of raw energy to empower the giant machina, Vegnagun. Shinra of the Gullwings suggests that the life energy flowing through Spira on the Farplane could possibly be harnessed for the purpose of supplying electricity to a city. In interviews published in the Final Fantasy X Ultimania Ω and Final Fantasy X-2 Ultimania guidebooks, scenario writer Kazushige Nojima and producer Yoshinori Kitase revealed that Final Fantasy VII and Final Fantasy X-2 share a plot-related connection, in which the Shin-ra corporation in Final Fantasy VII is founded on another planet after about one thousand years, after space travel became possible, by descendants of Shinra of the Gullwings in Final Fantasy X-2. This connection was conceived of only after Final Fantasy X was already finished and realized in Final Fantasy X-2 riding on the success of the original game and is not reflected in the gameplay or storylines of Final Fantasy VII or Final Fantasy X. Religion Religion is an important part of life for many of the peoples of Spira, with a large majority of the population describing themselves as "Yevonites." Though by the end of Final Fantasy X some people had begun to question them, nevertheless the teachings of Yevon were millennium-old and heavily influential. The Yevonite clergy taught that Sin was a divine punishment set upon the people for their pride in the use of machines. As a result, the temples forbade the use of modern technology, and promoted a culture of atonement for past sins in the hopes of appeasing Sin. While the Yevon church forbids most machina including weapons, their capital Bevelle retains machina to ensure its dominance. The Al Bhed are seen as dangerous to the Yevon clergy because they use machina and pose a threat to the church's uncontested control of Spira. The church retains its power by role in using the Final Summoning which results in the sacrifice of the summoner and her guardian to prevent its secrets from being divulged. Though Yevon set up Operation Mi’ihen to instill further loyalty to the teachings by making the Crusaders use machina that would never win against Sin. By the end of Final Fantasy X, the Yevon religion was effectively disbanded once evidence of its corruption was discovered, and its remaining priests volunteered the truth. Half a year later,