A thermochromic writing instrument including a writing body, storing a thermochromic ink therein, stored in a barrel; an operation body provided in the barrel to be operated to longitudinally move the writing body; a nib of the writing body configured to be capable of appearing from a front end of the writing instrument, wherein the writing instrument 1 further includes a friction unit, for rubbing handwriting in the thermochromic ink and capable of thermally changing the color of the handwriting by frictional heat generated at that time, and at least one clip body as the operation body, the friction unit 10 is provided at a rear end of the barrel, and the clip body is provided in an area other than the rear end of the barrel.

A multi-purpose combination writing instrument comprising: at least three individual writing instruments, each individual writing instrument comprising a barrel having a proximal end and a distal end; a base having opposing first and second ends, the first end of the base comprising at least three receivers, wherein each receiver is adapted to receive the proximal end of the barrel of a corresponding individual writing instrument, and the second end of the base having at least three tape flag platforms disposed therein; and a cap rotatably mounted on the second end of the base over the at least three tape flag platforms, wherein an opening in the cap provides access to one tape flag platform at a time as it rotates around the second end of the base.

A multi-purpose combination writing instrument comprising: at least three individual writing instruments, each individual writing instrument comprising a barrel having a proximal end and a distal end; a base having opposing first and second ends, the first end of the base comprising at least three receivers, wherein each receiver is adapted to receive the proximal end of the barrel of a corresponding individual writing instrument, and the second end of the base having at least three tape flag platforms disposed therein; and a cap rotatably mounted on the second end of the base over the at least three tape flag platforms, wherein an opening in the cap provides access to one tape flag platform at a time as it rotates around the second end of the base.

A knock type writing tool is provided, in which an appropriate amount of air can be taken in depending on an amount of a thermochromic ink discharged from a pen tip, so that the thermochromic ink can be smoothly discharged from the pen tip, and in which a writing body can rotate surely in conjunction with a rotation of a rotating member. An air hole 63a and a plurality of projection pieces 63b are provided at a rear end portion of a writing body 6. A front surface of a projection and retraction rotating member 7 is provided with a plurality of abutment parts 73, on which respective rear ends of the plurality of projection pieces 63b are to abut, and with a plurality of protrusion parts 72, each of which is formed between the plurality of abutment parts 73 and protruded more forward than the plurality of abutment parts 73. The protrusion parts 72 are respectively inserted in gaps 63c between the projection pieces 63b. An axial length of each projection piece 63b is longer than an axial length of each protrusion part 72, so that a portion of the gap 63c is left more forward than a front end of each protrusion part 72.

A knock type writing tool is provided, in which an appropriate amount of air can be taken in depending on an amount of a thermochromic ink discharged from a pen tip, so that the thermochromic ink can be smoothly discharged from the pen tip, and in which a writing body can rotate surely in conjunction with a rotation of a rotating member. An air hole 63a and a plurality of projection pieces 63b are provided at a rear end portion of a writing body 6. A front surface of a projection and retraction rotating member 7 is provided with a plurality of abutment parts 73, on which respective rear ends of the plurality of projection pieces 63b are to abut, and with a plurality of protrusion parts 72, each of which is formed between the plurality of abutment parts 73 and protruded more forward than the plurality of abutment parts 73. The protrusion parts 72 are respectively inserted in gaps 63c between the projection pieces 63b. An axial length of each projection piece 63b is longer than an axial length of each protrusion part 72, so that a portion of the gap 63c is left more forward than a front end of each protrusion part 72.

In one embodiment, a writing instrument refill includes a first portion having flexibility, and a second portion having a cross-sectional area larger than a cross-sectional area of the first portion, wherein the center of figure of the cross section of the first portion is offset from the center of the figure of the cross section of the second portion, the first portion and the second portion are formed integrally, and a part of the first portion has an outer diameter smaller than an outer diameter of the other part of the first portion.

In one embodiment, a writing instrument refill includes a first portion having flexibility, and a second portion having a cross-sectional area larger than a cross-sectional area of the first portion, wherein the center of figure of the cross section of the first portion is offset from the center of the figure of the cross section of the second portion, the first portion and the second portion are formed integrally, and a part of the first portion has an outer diameter smaller than an outer diameter of the other part of the first portion.

Provided is a retractable writing instrument including a pen point, a barrel, and a clip. The pen point is configured to be in a state of projecting from the barrel or a state of being retracted into the barrel by sliding the clip in a longitudinal direction of the barrel. The clip includes a clip body extending in the longitudinal direction of the barrel, a ball portion provided on a front side of the clip body and projecting in a direction of a surface of the barrel, and a clip base provided on a rear side of the clip body and is configured to produce a biasing force in a direction of a surface of the barrel. The surface of the barrel includes a guide groove extending in the longitudinal direction of the barrel and provided with a pair of side surfaces to restrict lateral movement of the ball portion, and the guide groove has a through groove capable of causing the ball portion to be in a noncontact state in a direction of the biasing force at least when the pen point is in the retracted state.

Provided is a retractable writing instrument including a pen point, a barrel, and a clip. The pen point is configured to be in a state of projecting from the barrel or a state of being retracted into the barrel by sliding the clip in a longitudinal direction of the barrel. The clip includes a clip body extending in the longitudinal direction of the barrel, a ball portion provided on a front side of the clip body and projecting in a direction of a surface of the barrel, and a clip base provided on a rear side of the clip body and is configured to produce a biasing force in a direction of a surface of the barrel. The surface of the barrel includes a guide groove extending in the longitudinal direction of the barrel and provided with a pair of side surfaces to restrict lateral movement of the ball portion, and the guide groove has a through groove capable of causing the ball portion to be in a noncontact state in a direction of the biasing force at least when the pen point is in the retracted state.

A multi-purpose combination writing instrument comprising: at least three individual writing instruments, each individual writing instrument comprising a barrel having a proximal end and a distal end; a base having opposing first and second ends, the first end of the base comprising at least three receivers, wherein each receiver is adapted to receive the proximal end of the barrel of a corresponding individual writing instrument, and the second end of the base having at least three tape flag platforms disposed therein; and a cap rotatably mounted on the second end of the base over the at least three tape flag platforms, wherein an opening in the cap provides access to one tape flag platform at a time as it rotates around the second end of the base.