Here's some ideas of a cool Naruto and PJO crossover that

Note: the terms kami and god/gods are interchangeable here, which ever sounds better - just kami has no plural and refers to other divine spirits too, and capitalised words refer to places. Also a Japanese language rule for accuracy, if you're going to make new words, when combining the word kami with another Japanese word it changes to shin - examples later in this text. It still means god but it's just how compound words work in the language.

Sorry if anything turns out inaccurate, I'm a fan of both but I'm not really a lore person, plus combining these two is already a stretch ha ha.

- General Overview -

The location/setting is made up - the land of Gods is north of the land of Earth and separated by a large rock mountain range always covered in thick cold mist. It's a very large land area and near the borders on each end are two hidden villages, the hidden village of Kami and the hidden village of Roma (or just the first one I'm not sure). In Kami, Percy is the shinkage and in Roma, Reyna is rakage. The two regions have two sphere of leadership, some parts overlapping and some parts not being ruled at all. Kami's headband symbol is a wing (like a Pegasus wing) and Roma's symbol is a dagger (like a roman pugio).

There are other protected small villages of smaller populations and without kage/leaders. There are also other (legendary maybe ) villages with other characters from the books like driads, nymphs or cyclops, though humanised a little to be just slightly altered from humans like fur or being blinded in one eye - adding features like villages to visit make a story more interesting and realistic but I'm not adding too much right now.

There is a variety of different chakra natures across the region, excluding fire which rarely appears if ever as a primary nature but sometimes as a secondary nature. Some villages (like cyclops as Poseidon's children) are more likely to have a particular chakra nature than the other four. Ying and Yang chakra also appears imbalanced in some areas and can be used in jutsu.

There is a god release (Shinton) technique with its own jutsu but these mostly are techniques for greatly altering elemental techniques to mimic godly powers seen in PJO and need the chakra nature of the user to match the chakra for the technique i.e. Water chakra for a water god technique. Naturally, more powerful gods have difficult techniques to master.

As past of history, these techniques were written long ago [authors of the scrolls can share the names of Greek and roman warriors or philosophers as needed] and passed down which some difficult to obtain/forbidden (i.e. Ones that mimic Kronos or other enemies of the gods).

To do the technique, you first call out the regular technique and then the first title of the god - god of streams would be a weaker technique than god of oceans. You would have to look up the most appropriate title but only one for each god or it gets long.

Naturally the seven and a few others know the more powerful techniques. Leo with a fire nature can use the fire technique to use both fire release and the god of fire, forges or hearth techniques.

The chakra needed for techniques of the gods can be more than one (i.e. Some techniques need one nature and others can use another nature) and needs a little thought to cover all of them but I'll supply the strongest god techniques I can think of, most important nature first.

Zeus - lightning, wind

Poseidon - water

Hades - earth, fire

Apollo - yang, wind

Artemis - earth, yang

Ares - lightning, earth

Demeter - earth

Hephaestus - fire

Athena - wind

Aphrodite- yin

Hera - lightning, water (just because?)

Hestia - fire, yang

Dionysus - earth, water

Hermes - wind, yin

You can pick one of these and chose a title and chakra nature- /gods/

Of course, roman gods can feature too! (they just might need a different title in their techniques to not confuse people maybe) -

By the way, in the land of Gods, knowing a weaker god technique is common and expected in the population from the age of 12 (I think that's the age the demigods start to get noticed right?) so any opponents or allies from the country will have one of these. The rare thing is super powerful gods like the ones I listed.

- specifics in my own view -

I was considering the appearance of the two villages, which can either be the original PJO appearances that will kind of clash with the Naruto style or.. Kami will have the traditional Japanese one floor style homes surrounding a ring of larger important clan buildings on a wide road that are two floors or more. There are shrines to the gods along this street and these are modified from traditional Japanese shrines to feature a wooden statue of the god and small fire for offerings and lighting incense. Roma is situated across a large river in the wide valley of seven hills with taller, modern buildings with modern glass and architecture - its god worship comes in the form of small stone statues in every home and office with a scented candle and money donation box that gets collected by the council to help fund the city's many festivals for the gods.

Within Kami the taller buildings in the centre are numbered head offices for different sectors of industries (head of construction, medicine, education, agriculture) and not actually homes. All the homes have the traditional tatami mats and such. There is a very large but un-gated complex of homes at the end of the main road for the shinkage and the most important demi-gods (but they're not actually demi-gods in the sense of being their children - you can call them demi-gods for knowing the god release techniques if you'd like).

Surrounding Kami are extensive fields of strawberries that are the largest in the naruto world and supply the rest of the country as well as sometimes the land of earth and further like the land of grass or rain if they last long enough. Perhaps our main characters discover this and use the traders routes to cross over into the land of gods.

Similarly Roma's area has the large hills I mentioned which have grapes and olives that they use simply or make oils and wines. Instead of going through the mountain, Roma is near the coast and uses the river to ship the food in the sea and around the mountain barrier. These preserve better and go all the way to the land of wind, fire or water but not often.

Cronos' technique can come from a dojutsu with a golden eye that is passed down (not genetically. The gory way that ninja do when they steal sharingan or others). There is only one pair said to come from the titan himself and are naturally a pale gold with a regular black pupil which become two black triangles (opposite each other.. look up the shape of an hourglass, that's what I mean) that spin around each other when activated. The dojutsu can be called Jikangan (jikan is Japanese for time) and only needs one eye to be able to use the technique - this is the ability to slow time surrounding the user, look a few minutes into the future, or rewind time up to a minute in the past. Last one might need some explanation in that, if he rewinds time after he for example experiences an injury, his body is rewinded and everyone else's to their previous positions and no one else will remember that a different future occurred except the jikangan user. These three abilities might need nerfing maybe to be more defeatable but it is a rare dojutsu so I'm leaving it at this for now.

The oracles' sight can also be a dojutsu called atogan (ato being a way to say future) or perhaps some kind of possession from a spirit, I'm not sure though - I don't want to add too many dojutsu.