Kongōsōha

is a special attack that launches shards of diamond (known by the more archaic term adamant in the Feudal era). The technique originally belonged to Hosenki, who passed the technique on to the Tessaiga after its user InuYasha proved his worth by choosing to save his friends over strengthening his sword.

The Kongosoha is able to pierce the strongest barriers, including Naraku's barriers. The attack is not unbeatable, however; it is unable to pierce the armored shelled of Meioju. The Tessaiga can only use the technique by transforming into its Diamond form.

Later in the manga the yokai Moryomaru tricks InuYasha into using the Kongosoha on a Meioju (turtle yōkai) and then absorbs the yokai along with the diamond shards on its armored shell, thus giving him the ability to use the Kongosoha. After Naraku absorbs Moryomaru he also gains the use of Kongosoha and is able to add his shoki to the Kongosoha to make it more deadly.

THis technique cannot be used in the modern era, likely to prevent unlimited wealth.