Who he was
Evidence grade: Traditional · Later accountsThe record on Matashichirō is thin. His name is written 又七郎, Matashichirō. The 1654 monument calls him a Yoshioka and gives him one act: he gathered the Yoshioka pupils.
His age is not recorded in any early source. His kinship is not recorded either. A book of 1755 calls him the son of Seijūrō, but a research site treats that as a guess. A seventeen-year-old Matashichirō and a child in armour come from novels of 1932 and 1967, as a scholar's commentary describes them. Those are fiction.
A 1716 book names a different Yoshioka, Matasaburō (又三郎), a son of the house who died in 1614. The two names are close, but the sources give them separately.
The film shows him as an adult. That is a design choice.
The road to the fight
Evidence grade: Traditional · Later accountsThe 1654 monument says the Yoshioka pupils nursed a grudge. They whispered that by skill he could not be opposed, and that they should plan in the tent.
Then, the monument says, Matashichirō, "under pretext of martial practice", brought several hundred pupils together at a pine tree outside the city. They carried weapons and bows and arrows. Their aim was to kill Musashi suddenly.
"Several hundred" is the monument's claim, and it cannot be checked. One museum text says the real number was dozens or about 150. A version in a later Kumamoto biography says dozens.
Where the pine was is also uncertain. The monument says only "outside the city". The name Ichijōji appears first in a note in the 1755 book. Kyoto City records a rival site.
The pine
Evidence grade: Traditional · Later accountsThe monument says Musashi had "a gift for knowing things beforehand". He sensed the plot and quietly told his own pupils to stand aside. To him, the crowd was like floating clouds. When he scattered his enemies, it was like hounds chasing a fierce beast. He came back into Kyoto in triumph.
The monument says nothing about what happened to Matashichirō. It describes no single exchange and no number of dead.
A Chikuzen book of about 1727 adds more. In it the Yoshioka carry spears, naginata and bows. Musashi has ten-odd pupils. A seventeen- or eighteen-year-old rushes ahead and is hit by an arrow. Musashi tells the rest to withdraw calmly. He fights on alone, retreating through the crowd, until city officials stop it.
The film tells the pine fight from the 1727 book, then gives the monument's version. The movements on screen are the film's own invention.
After, and how we know
Evidence grade: Traditional · Later accountsThe famous version, in which Musashi comes before dawn and cuts Matashichirō down, is later. It appears in books of 1755 and 1776 as a story Musashi was said to have told. The oldest account, the 1654 monument, says nothing of a killing. The film says so.
The monument says the Yoshioka martial house was finished. Other records say the family did not vanish. A 1716 book names Yoshioka Matasaburō, a son of the house, who in 1614 drew a hidden blade at the Imperial noh and cut down guards before he was killed. The court record the book quotes describes that incident but does not name the Yoshioka.
We do not know what became of Matashichirō. The sources do not say.