Takamaru

Takamaru is the protagonist of The Mysterious Murasame Castle. His design is heavily based on historic samurai warriors.

Super Smash Bros. series
In the Super Smash Bros. series, starting with Super Smash Bros. for Nintendo 3DS / Wii U, Takamaru has appeared as an Assist Trophy. He attacks by quickly slashing with his katana and by throwing shurikens.

In Super Smash Bros. Brawl, there is a sticker of Takamaru.

In Super Smash Bros. Ultimate, there is a spirit of Takamaru.

Captain Rainbow
In Captain Rainbow, Takamaru is one of the inhabitants of Minmin Island. His first encounter with the protagonist, Nick, involves him calmly meditating before slicing a falling leaf into pieces. Afterwards, Takamaru teaches Nick how to meditate. He later asks Nick to visit Tracey for some medicine for an injured Minmin, though she then gives Nick a letter that asks Takamaru to directly come to her. After he reads it, he reveals that he gets anxious around women, and is later seen practicing hugging a dummy, as if it was Tracey. Giving him one of Tracey's bras leads to him attaching it to the dummy and becoming more confident, and he then makes his way to Tracey's mansion.

Once there, he suddenly gets nervous again, but Nick pushes him up the stairs to confront Tracey. He walks up to Tracey and asks for his medicine, but Tracey tells him to kiss her shoe. He bends down to do so, but Tracey stops him and tells him that she wanted to see if he would swallow his pride. Telling him that she respects him, Takamaru gains the medicine he needs and leaves. He is later seen at a womanly statue (where he meditated previously), and destroys it, showing that he's overcome his uncertainty with women. He thanks Nick for his help, creating a friendship bond with him.

WarioWare: D.I.Y.
One of WarioWare: D.I.Y.'s Japan-exclusive microgame, Murasamejō, Takamaru is under attack from ninjas who throw shuriken at him. At the right time, the player has to tap him to make him invisible, letting him dodge the projectile. If Takamaru gets hit, he gets knocked out, losing the microgame.

Nintendo Land
In Nintendo Land, although Takamaru did not make a physical appearance, the minigame Takamaru's Ninja Castle is based on The Mysterious Murasame Castle, and the gameplay, which involves throwing shuriken, is based on Takamaru's ability to do so.