The Piledriver is the ultimate weapon in immortal purification. It is a rather large type of weapon and is operated through the use of multiple machines, called solar generators, the use of solar energy, and a child with solar blood in his/her veins. There are a number of variations of Piledriver, as the system changes in each game. Despite this, the Piledriver has appeared in every Boktai game to date. In the Boktai series, Otenko is the only one with the ability to summon a piledriver.
 Variations of Piledriver
 Boktai: The Sun is in Your Hand
In Boktai: The Sun is in Your Hand, the Piledriver is in its most standard form. It is activated by dragging the immortal's coffin into the centre of the piledriver, then firing a solar spread at 2 or more solar generators. This will cause the Piledriver to go into a sort of standby mode. To activate it, the sun must be striking the solar sensor. The player must walk over the sol symbol at the bottom of the Piledriver, and press A.
The purification process will start. To purify the immortal, the player must avoid the immortal's attacks and keep the solar generators working. This can be done by firing solar spreads at them, and a shortcut is to fire into the centre of the Piledriver. This will power up all solar generators in the current Piledriver. The immortal's health (the red bar in the top left) is diminished depending on the strength of the solar generators and, ultimately, the sun. Once the immortal is weakened and vulnerable, the music will change and the immortal's cries will change, becoming more frantic. This means that the purification is almost done. Once the process is complete, the music will stop, the immortal will speak its last words, and will let out a final wail. You will be given a rank for the completion of the dungeon. With the immortal purified, the Piledriver will become inactive and cannot be used again.
The Piledriver is used in a different way when fighting the Queen of Darkness and the ultimate immortal, Hel. This time Otenko has to summon the solar generators one by one. The player must defend Otenko from Hel's strikes until all 4 generators are summoned. When they are summoned, the player must use a wild bunch attack; hold down B in the centre of the Piledriver. When this fails, Sabata joins you in using the wild bunch attack. However, to do this you must defeat the newly transformed Hel's hands. A final wild bunch will destroy Hel.
 Boktai 2: Solar Boy Django
In Boktai 2: Solar Boy Django, the Piledriver is slightly different to its predecessor. The activation of the Piledriver is the same process as before (except you strike the solar generators rather than fire a spread at them), however the purification process is different. This time there are always 4 solar generators and instead of letting the generators do all the work, you must try and keep the immortals away from the generators by striking them, because if an immortal reaches the solar generator and stays on it long enough, that generator will deactivate and you have to strike it again to activate it. If all the solar generators are deactivated, the immortal will try to escape from the Piledriver. If this happens, just drag the coffin back to the centre. Again, when the immortal is weakened, the music and cries will change, and likewise with the ending process. Unlike the previous game, the Piledriver stays summoned in one, central place throughout the duration of the game.
In a turn of fate in Boktai 2, Sabata must purify Django in the Piledriver since he was bitten by Ringo. Sabata can use the Piledriver, but at a very high risk; although he has solar blood in his veins (able to activate the piledriver), it is overwhelmed by the dark matter inside him, meaning that he risks death. Since Sabata is steadily damaged by direct sunlight, this makes the purification process much more difficult. However, the use of sunblock during the purification process prevents Sabata from receiving damage, making it much easier to purify Django. Once purified, Django emerges from the coffin as Black Django.
When Django is fighting Jormungandr, the citizens of San Miguel all give their energy to Zazie, who channels it through to Django through the Piledriver. This gives Django enough energy to absorb sunlight with which to destroy (and seal away) Jormungandr.
 Boktai 3: Sabata's Counterattack
The Piledriver system in Boktai 3: Sabata's Counterattack is, in principle, the same as it was in Boktai 2: Solar Boy Django. The only differences this time would be that the new features of the Gun del Sol allow for easier use of the Piledriver; for example, the Wizard frame returns, which shoots in 5 different directions, allowing the player to hit all solar generators from a distance. A frame which also sends out a form of sonar wave allows the user to get the Immortal back into the coffin for quicker purification. Another notable change is that the music has been changed, with the inclusion of additional instruments such as harder percussion, church bells and organs. This gives the battles a much more intense tone.
This also marks the first/only time that Sabata is purified in the Piledriver. He asks Django to purify him to free him from Ratatosk's control. However, the exact opposite happens; since Sabata's soul has been purified, he is now able to be used freely as a puppet by Ratatosk. He emerges from the coffin completely unconscious and is taken away by Ratatosk.
This variation of the Piledriver is otherwise the same as its predecessor. Ratatosk is the only immortal that does not need to be brought to the beginning of the dungeon to be purified; instead, the purification process begins straight away.
 Lunar Knights
The Piledriver system in Lunar Knights is entirely different from the Piledriver in the Boktai games. First, it is not the large circular array imprinted on the ground it used to be. It is now a giant satelite in space that absorbs its energy from the sun. It is operated by the new sunflower girl, Alice. Second, it is a LONG way to the Piledriver. The player - controlling Lucian and Aaron aboard the mobile fighter Laplace - must fight their way through space, defeating fleets of ships while keeping up energy and life, until they meet the boss at the end. This is usually Perrault. When Perrault is defeated, Laplace will send the coffin to the Piledriver. There will then be a cutscene showing the immortal being purified, and then the player earns 1 (or 2) terrenials; the player does not actively take part in the purifying process beyond traveling to the Piledriver.
The piledriver itself, simply named Sunflower in the English release, works with the use of numerous satelites and mirror panels. The panels absorb solar energy from the sun and use it to purify the vampire in the coffin. This is the only possible way to purify a vampire since the paraSOL was implemented.
Also, this Piledriver acts as the docking bay for Laplace when it is not in use (though it also docks with it when a Vampire is ready for purification).
As with the other games, there is a final variation to the Piledriver system. This is against the immortal Polidori. The player strikes Polidori with Laplace's cannons and eventually, Laplace goes inside the body of the enlarged Polidori. Laplace destroys his insides and it is believed that Polidori is defeated and purified.
Though it seems to have nothing in common with the Piledriver of the past, there is one connection; this Piledriver generates a circular array (presumably composed of solar energy) to suspend the coffin in space, which is very similar to(if not the same) the array of the old Piledriver.