The first idea I got while reading the first chapter of a High School DxD x Final Fantasy IX story, Black Mage of Kuoh By: Quatermass ( https://www.fanfiction.net/s/11897451/1/Black-Mage-of-Kuoh ) & listening to this:
1.
It's where Issei is the reincarnation of the original Godzilla/Kiryu, whose soul came from another dimension. He's triggered by hearing the roar of Godzilla from a movie (yes, in this story, the Godzilla movies exist in High School DxD world). Also in this story, Issei isn't a pervert. Also, he's discovered his Sacred Gear on his own.
2. Second Idea, I got from listening to this:
Here, Issei is the adopted human son of Mothra. How this comes to be? It starts out in 2002 or 2003 as a very young Issei (probably around 3 years old) is on a cruise with his parents in the south of Japan. A storm strikes & sinks the boat. He's washed away & his parents killed. He eventually washes up on Infant Island. He's found the natives. They bring him to Mothra to decide wha

==Jurassic Park Europe or Italy (Santa Guiera, Santa Raiza, Ticos Island)==
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This is the the only InGen Park which has no Dinosaurs, meanwhile it had plans to make it a Safari Park called "Ice Age Safari Park". The fauna here is Pliestocene Glacial European fauna. But some animals are also from North America "Bering Strait". This is in the cold areas of Santa Guiera which is the biggest Island of the archeipliago. The warmer areas which are near the sea are home to Pliocene and Pliestocene Interglaccial mammilian fauna. Some animals are said to migrate. There are ven some mordern animals on this Island. The other warmer Island Santa Raiza which has higher Temperature is home to Permain and Early Triassic Fauna from Europe. Ticos island is whom to the prehistoric animals which were affected by Insular Dwarfism and Insular Gingantism. The Island is also home to mordern extinct animals. 
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===Ice Age Park (Cold)===
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*Woolly mammoth
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Jurassic Park II (Las Tres Hermanas)
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The fauna here is only South American and Austrailian. The animals here had been isolated since many millions of years and that is why this is a special park for them. The is the Hermanas Sea surrounding these three islands which is a water resort and is home to sea mammals of the Cenozoic. Dinosaurs and other Prehistoric reptiles live in the Islands of Las and Tres. Meanwhile the mammals live on Hermanas.
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===Las and Tres (Phase I)===
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*Abelisaurus
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*Alvarezsaurus
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*Massospondylus
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*Aerosteon
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*Amargasaurus
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*Prionosuchus
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*Anabisetia
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*Argentinosaurus
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*Puertasaurus
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*Futalognkosaurus
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*Irritator
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*Antarctosaurus
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*Aucasaurus
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*Austroraptor
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*Buitreraptor
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*Brachytrachelopan
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*Carnotaurus
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*

Jurassic Sea World or Marine Facility (Muertes Sea)
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This is a vast stretch of ocean covering the five deaths. The sea is made up of Mesozoic and Paleozoic animals. Along with the animal in the marine facility, In-Gen planned to open up and exhibit near the five deaths called the Jurassic Sea World. Here prehistoric sea monsters live.
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*Anomalocaris 
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*Archelon 
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*Aristonectes
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*Bananogmius 
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*Brontoscorpio 
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*Cladoselache 
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*Cretoxyrhina 
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*Cryptoclidus
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*Dunkleosteus
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*Enchodus 
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*Hesperornis 
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*Ichthyosaurus
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*Isotelus
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*Jaekelopterus
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*Kronosaurus
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*Leedsicthys
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*Nothosaurus
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*Orthoceras 
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*Psephoderma 
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*Stethacanthus
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*Tanystropheus
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*Ha