Ahh! It's the Giant Armored Octopus! ...Oh, he's named Tako?
This article is about a subject that has not been officially named in any official Katekyo Hitman Reborn! translated material; the current title is merely a placeholder.
The Rain Tube is one of the Rain-attribute Box Weapons of the Sistema C.A.I. owned by Hayato Gokudera.
Description
It is an ammunition for the Flame Arrow. It provides a coating of Rain Flames around the bursts of Storm Flames usually shot by the weapon. The Tranquility characteristic weakens enemy defenses, allowing the Storm Flames to inflict damage with their Disintegration characteristic.