Ecstasy Hybrid is the ultimate hybrid and the highest form of Climax Hybrid.
Overview[]
During the final battle against Thanatos, Kizuna was killed by the last machine god while protecting Aine. Fortunately, Hida Nayuta had prepared for this by recruiting help from the three former Machines Gods. While Hokuto kept Thanatos at bay, Odin repaired Kizunas' body and Osiris prevented his soul from fully passing on. To fully ensure Kizuna's revival, Osiris preformed Ecstasy Hybrid with Kizuna to make sure he had enough life force to come back. Furthermore, Osiris would also teach Kizuna the method so he can use it to defeat Thanatos.
Unlike all the other forms of Hybrid, Ecstasy Hybrid is the only one where Kizuna has sex with another Heart Hybrid Gear pilot. This is because Ecstasy Hybrid requires Kizuna to directly climax into the woman's womb, the same way that's used to make a child. This results in both Kizuna and the female partner gaining an unbelievable boost in all their abilities that surpasses even the power of a machine god. When Kizuna did Ecstasy Hybrid with Aine, Kizuna became too fast and strong for Thanatos to even fight back. Likewise, Aine became strong enough to break Thanatos's sword and her weapons (Pulverizer & Code Breaker) and were able to counter the machine god's attacks.
If the partner has a Ros-series Heart Hybrid Gear, they won't get pregnant with Kizunas' child. This because all the "life" that Kizuna is releasing into their womb is being transferred into energy for the core. However, there is still a very rare case where the woman can get pregnant. In that event, the core will be safely ejected out without killing them. For other series, it seems the pilot also has low chances of getting pregnant, as Ragrus still had Demon two months later after doing Ecstasy Hybrid with Kizuna.
Along with all the previous advantages, Ecstasy Hybrid is noticeably the most pleasurable Hybrid of them all. Almost all the women who have done it with Kizuna have even gone as far as to request he does Ecstasy Hybrid with them, even when it wasn't needed and wish to do it as long as possible (Zelshione wanted to spend an entire night doing it with Kizuna after their first time together). Since returning to their world, all the female members of Amaterasu and Reiri usually try to spend most of their free time when they're with Kizuna to do Ecstasy Hybrid, simply because they want to do it.
As an unexpected side effect, the bodies of the women have been growing noticeably more erotic, excluding Sylvia. As well, the breast milk of those who have gotten pregnant becomes highly concentrated life energy, which can be used to repair any malfunction in Genesis or Eros. Likewise, Kizuna's "thing" during Ecstasy Hybrid slowly but noticeably becomes larger and larger. The change isn't permanent, unlike with the changes to women's bodies, and Kizuna clarifies he has no control over it and is unable to stop it growing even if he wants to; the only way to stop it and revert to normal size is to stop doing Ecstasy Hybrid, otherwise it will keep getting growing, which leads to concerns from women about whether they can handle or be hurt by the increasing-size.