Ioneos is like Kuon's &quot;older brother,&quot; as he and Kuon are created from the same type of magical crystal. However, Ioneos' appearance and size are much larger and sleeker than Kuon's because he is comprised of an entire crystal, save a small chipped fragment which Kuon is made from. He was sealed inside of one of the school's stone pillars until Hikari accidentally released him during a routine fire drill. The entire school was subsequently demolished after the blast following Ioneos' release. Jennifer nicknamed him &quot;Oniita,&quot; saying that his original name was too long. In the end, Ioneos turns into mud along with Kuon and become crystals. Kuon being the little chip and Ioneos being the big crystal. Jennifer puts them on a necklace and wears the crystal.    from wikipedia

High school student Takeru Takemoto works part time as a (motor)bike courier. During one of his deliveries, he saw a mysterious light passing him and fell into a forest. What he had found was a beautiful girl coming out from a glowing cocoon, calling herself "Hikari." While Takeru was quite embarrassed because of Hikari's nudity, a strange monster suddenly showed up and immediately attacked the two. Both Takeru and Hikari demonstrated the power of their other selves before Takeru had a clue of what's going on.
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(Source: Anime News Network)


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