A nib for a refillable free ink writing felt pen includes a body and a dry ink tank including dry ink, the dry ink tank being delimited by the body of the nib and a dry ink tank wall including a breakable portion.

A nib holder. The nib holder includes a case having a nib insertion slot. A slider is contained within the case and has a plurality of connection pins and slider connection threads. A pusher is contained within the case and has a plurality of sliding slots. The pusher utilizes the sliding slots to establish a sliding connection to the slider via the slider's connection pins. A stopper is contained within the case. The stopper prevents horizontal motion of the pusher but permits vertical motion of the pusher. An adjuster has adjuster connection threads and utilizes the connection threads to mesh with the connection threads of the slider to establish a threaded connection. A nib is connected to the nib holder by insertion of the nib into the nib insertion slot and then rotation of the adjuster to raise the pusher vertically so that the nib is compressed between the pusher and the case.

A nib holder. The nib holder includes a case having a nib insertion slot. A slider is contained within the case and has a plurality of connection pins and slider connection threads. A pusher is contained within the case and has a plurality of sliding slots. The pusher utilizes the sliding slots to establish a sliding connection to the slider via the slider's connection pins. A stopper is contained within the case. The stopper prevents horizontal motion of the pusher but permits vertical motion of the pusher. An adjuster has adjuster connection threads and utilizes the connection threads to mesh with the connection threads of the slider to establish a threaded connection. A nib is connected to the nib holder by insertion of the nib into the nib insertion slot and then rotation of the adjuster to raise the pusher vertically so that the nib is compressed between the pusher and the case.

A nib for a refillable free ink writing felt pen includes a body and a dry ink tank including dry ink, the dry ink tank being delimited by the body of the nib and a dry ink tank wall including a breakable portion.

The present invention includes: a shaft cylinder having an opening at a front end thereof, a tip holder movable in an axial direction of the shaft cylinder, a tip projectable and retractable in conjunction with a movement of the tip holder, an annular member loosely fitted onto an inner periphery of the opening of the shaft cylinder to be movable in an axial direction of the shaft cylinder with respect to the shaft cylinder, and an elastic member capable of connecting the tip holder and the annular member such that the tip holder and the annular member are movable relatively to each other. A contact surface tapered toward the front end is formed on at least a part of an outer periphery of the annular member. A cutout is formed at a part of the annular member such that an inner diameter of the annular member is reduced when a load is received by the contact surface. A guide surface tapered toward the front end is formed on the part of the inside surface of the shaft cylinder. The contact surface is configured to receive the load from the guide surface in conjunction with the movement of the tip holder toward the front end side.

An attachment structure in a writing instrument, includes: a first component; and a second component configured to be fitted into a fitting hole provided at an end of the first component, the second component including: a small-diameter portion; and a large-diameter portion disposed in front of the small-diameter portion; and a first outer step portion disposed between the small-diameter portion and the large-diameter portion, the fitting hole including: a small-diameter hole portion; and an inner step portion disposed in front of the small-diameter hole portion, the small-diameter portion being fitted into or loosely fitted into the small-diameter hole portion, the first outer step portion coming into contact with the inner step portion, the small-diameter hole portion includes a barb portion protruding from the inner face of the small-diameter hole portion, the barb portion being deformable by contact with the small-diameter portion when the second component is fitted.