101Leafy researched the games.
BeastKingThunderbow

Hard Bow of Black Rajang pelt with a fiery aura. Normal people can't use it.
| Class | Bow |
|---|---|
| Rarity | 10 |
| Attack | 336 |
| Thunder | 130 |
| Slots | 0 |
| Price | 118,800z |
Upgrades
| Upgraded from | Beast Thunderbow |
|---|
Upgrade tree from モンスターハンターポータブル 2nd G 公式ガイドブック (Enterbrain, 2008), page 802.