It is believed that Sri Lakshmi Narasimhar came to this palce after hiranya vatham and stayed here for "ever" in this Yoga sayanam posture. It is well kown that Srinarasimha avathaaram took place at "Sri Ahobilam". However, since munivars requested the presence of Sri Narasimha here on an endless timescale, The LORD Narasimha chose to stay here for ever. This is also confirmed by thirumangai aazhwaar's reference to "thakkkaanai" in his paasuram presented in this article. Among all the other avathaarams this and the "vaamana avathaaram are the most significant becuase of the fact that they both accomplished the misssion instantly. Many of the LAkshmi Narasimha bakthaas believe that by praying to this LORD (who is an instant acccomplisher), their prayers are fulfilled instantly if not atleast an instant relief is offered without delay by this LORD. (An analysis is presented at the end of this thala puraanam on narasimha avathaaram and this shrine's importance as "kadigai" or instant reliver.). It is a belief that, One, would attain Moksham simply by staying here for one Kadigai (period of time) ie approximately half hour in this shekthram. Hence it is named Thiruk kadigai. It is believed that Saint Vishvaamitrar meditated for one kadigai on Lord Narasimhar and obtained his title "Brimha Maharishi" here. The Saptha Rishis and vaamathEvar came to this place and and started penance to have darshan of Narasimha Avathaaram, and the Lord fulfilled their wish within one kadigai of penance. Hence this hill is known as Kadikaachalam.
After Sri Raama avathaaram, aanchneYa wanted to go back to sri vaikundam, and serve the LORD there. The Lord instructed anchnEya to goto this place and protect the rishis penance from the oncoming danger. Two demons by name "kaalan and kEyan" appeared as soon as the rishis started penance and started to distrub their effort. Sri hanuman wanted an instant tool to stop it and Lord Rama offered him his changu and chakram with the help of which Hanuman killed the demons and prevented the tapas of saptha rishis and vaamathEvar . Hanuman also had the darshan of sri Narasimha in his avathaara kOlam at the lapse of a kadigai, and along with the rishis, and accepted the order of Lord Narasimha to sit in front of HIM in the small hill and serve as a protector for those whoever comes to this hills seeking relief from demons or demon effects.
It is believed that Lord Narasimha asked Hanuman to stay here until the end of the Kali yugam and reach him after that. There is no other place AanchnEyaa has such prominance, ( a hill and temple as his OWN abode) and also with changu chakram and with four hands.