Uncommon Japanese boy name starting with J

This is for a book I'm working on and I'm stuck on the character's name. he's going to go by a nick name but I need an uncommon Japanese boy name starting with J. I've gone through about a thousand websites with no luck. if anyone can help I would appreciate it.

Joen 【如燕】

If you want "uncommon", can't it be any made-up name? How uncommon or common do you need it to be?

How about Jun... various kanjis

https://en.wikipedia.org/wiki/Jun_(given_name)

How about Jiraiya or Jaruto

Juon Jurai Junku Janome Jasui Jaren Jion Juki Juku Jirai Jinta Jita Jusui Jonta Jasa Jaita Jara Jarata Jumoku Jitan Jigan Jirota Jiroumon Jirobe Junbe Joumon Jitaro Jotaro Jutaro Jiroemon Jintaro Jinkichi Joukichi Jirokichi Jinichi Jiroichi Junro

Jugemu.
Short for Jugemu jugemu goko no surikire kaijarisuigyono fuuraimatsu kuuraimatsu kuunerutokoroni sumutokoro paipo paipo.....
Oh, forget it!

Lol thenjoy recommendations crack me up.

I vote for Jaruto or Jugemu!！

Junta

Maybe already you know Japanese vowel is only あ、い、う、え、お(a,i,u,e,o).
Names starting "じ(ji)","じゅ(ju/jyu)" and "じょ(jo/jyo)" are not unusual,
but if make it a name that starting "じゃ(ja)" or "じぇ(je)",
the name will not be strange sound as Japanese name.(depends on readers)

For "じゃ(ja)" kanji may use "蛇" or "邪",
but as a meaning is not good, it depends on the personality of the character.
https://en.wiktionary.org/w/index.php?title=%E8%9B%87&oldid=42086274
https://en.wiktionary.org/wiki/%E9%82%AA
For "じぇ(je)" is no kanji, but it may be interesting to use
starting ざ,(じ),ず,ぜ,ぞ/za,(zi=ji),zu,ze,zo kanji instead.
Because it may be read so as dialects or kids pronunciation.

How about using a real address,rail station or bus stop name in Japan?
Search results are not all characters starting "J", but guess it will be big hints.
https://www.mapion.co.jp/
(input/copy to top search box)
http://busmap.info/
(input/copy to バス停をキーワードで検索 box)

And, personally "Jugemu" is no recommend.
BC, that name comes up in the story of famous "Rakugo".
https://en.wikipedia.org/wiki/Rakugo
https://en.wikipedia.org/wiki/Jugemu
A parent who is troubled to give a child's name is a story saying
that father wishes for happiness of a child and connects all the names super long name
like a "tongue twister/早口言葉" or "spells/呪文" of magic.
In 2017 winter(Jan-Mar as last cool/period) TV-animation
"Showa Genroku Rakugo Shinju" picked it up at episode 4 of season 2.
https://en.wikipedia.org/wiki/List_of_Descending_Stories:_Showa_Genrok...
https://youtu.be/4BX1zqenYFs
(this vid is official DVD/BD-set box sales promotoion, not full story)
So that name became known to core fans of Japanese anime in whole world already.